LIBRARY OF CONGRESS, 



V 






Chap. Copyright No... 

Shelf.......:... i 



UNITED STATES OF AMERICA. 




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A 
HANDBOOK 



OF 



ENGINEERING LABORATORY 
PRACTICE. 



BY 

r 



RICHARD ADDISON SMART, M.E., 

Associate Professor of Experimental Engineering, 
Purdue University. 



FIRS T EDITION. 
FIRST THOUSAND. 



<* i % • r/ 



y» 



<• 



NEW.Y0R.K*- / 
JOHN WILEY & SONS. 
London: CHAPMAN & HALL, Limited. 
1898. 



16845 



Copyright, 1898, 

BY 

RICHARD A. SMART. 






¥ 



^ 




TWO COPIES RECEIVED. 



ROBERT DRUMMOND PRINTER, NEW YORK. 



18 - . 



PREFACE 



THIS volume is intended primarily as a manual for 
the use of students in the routine of experimental 
wc>rk in Steam-engineering, Strength of Materials, 
anil Hydraulics. 

It may also serve in a limited way as a guide to 
those engineers in active service whose familiarity with 
the ordinary methods of testing is limited. 

The chief object in view has been to provide in 
convenient form such directions for the conduct of 
the various tests and experiments comprising the 
course as the student will need to enable him to take 
charge of and conduct the particular work assigned 
him in an intelligent manner and with little delay. 
With a large class of students beginning a variety of 
experiments at the same time it is essential that the 
directions be such as to make each student or group 
of students as nearly self-directive as possible. 

No attempt has been made, therefore, to preface the 
consideration of the subject from an experimental 
standpoint with an exposition of the theoretical con- 
siderations involved; it is assumed that the class-room 
work, which should be carried on in connection with 



VI PREFACE. 

that of the laboratory, will supply the theoretical in- 
struction. 

The methods of testing described under the various 
general heads are not intended to cover the subject in 
an exhaustive way. Only such tests have been 
described as may be carried on in connection with the 
complement of apparatus to be found in the better 
equipped laboratories of experimental engineering, and 
the methods explained are those which the author has 
found to be most easily employed in every-day prac- 
tice. Both the manner of arranging apparatus and the 
method of conducting the tests are capable of great 
variation to suit the needs of special investigations. 

Since the equipment of the majority of engineering 
laboratories does not permit all the students in a class 
to take up the course of experiments and tests in the 
same order, it becomes necessary to make the direc- 
tions for the various tests complete in themselves and 
avoid, so far as possible, reference to tests described 
in preceding sections. This necessitates the occasional 
repetition and duplication of directions which occur in 
the volume. 

Acknowledgment is hereby made of thanks due to 
Prof. W. F. M. Goss, for valuable assistance in the 
preparation of the volume; to Prof. W. Kendrick 
Hatt, who assisted in the preparation of the chapter 
on Strength of Materials; to Mr. C. H. Robertson, 
and to others who have aided in the completion of the 
work. 

R. A. SMART. 

Lafayette, Ind. 
Sept. i, 1S98. 



TABLE OF CONTENTS 



PAGE 

CHAPTER I. 
Introduction i 



CHAPTER II. 
Elementary Measurements 4 

CHAPTER III. 
Measurement of Liquids 21 

CHAPTER IV. 
Measurement of Gases 29 

CHAPTER V. 
Measurement of Pressure 33 

CHAPTER VI. 
Measurement of Temperature 40 

CHAPTER VII. 

Calorimeters 47 

vii 



Vlll TABLE OF CONTENTS. 



CHAPTER VIII. 

PAGE 

Measurement of Power 55 



CHAPTER IX. 
Strength of Materials 70 

CHAPTER X. 
Steam-boiler Testing 123 

CHAPTER XI. 
The Steam-engine Indicator 139 

CHAPTER XII. 
Steam-engine Testing 165 

CHAPTER XIII. 
Testing of Hydraulic Machinery 224 

CHAPTER XIV. 
Miscellaneous Tests 236 

APPENDIX. 

Tables, etc 257 

Index 277 



ENGINEERING LABORATORY PRACTICE. 



CHAPTER I. 
INTRODUCTION. 

1. The Laboratory Course. — The course in labo- 
ratory practice in Engineering is designed to familiar- 
ize the student with processes of investigation, to 
give experience in the conducting and reporting of 
experimental engineering work, to secure data which 
shall verify and supplement theoretical instruction, 
and to give a practical knowledge of the construction 
and management of machinery and apparatus. 

2. Method of Instruction. — The method of in- 
struction should be such as will throw the investi- 
gator, as far as is practicable, on his own resources, 
giving only such directions as are necessary to facili- 
tate the work and secure uniformity of results. 

Since the working up of the data obtained is an 
extremely important part of the work, it is desirable 
that this be done under the immediate direction of the 
instructor. The time required to work up the data 
and prepare the report should be considered when 
grading the reports, in connection with the accuracy 
of the results and the proficiency shown in the con- 



2 ENGINEERING LABORATORY PRACTICE. 

duct of the test and the management of the ap- 
paratus. It will be found convenient to record the 
dimensions and constants of the various pieces of 
laboratory apparatus in a book which may be kept at 
hand for convenient reference. This book will be 
referred to in what follows as the " Commonplace- 
book." 

3. Care of Apparatus. — One mark of a good en- 
gineer is the care which he exercises in handling ma- 
chinery. While to the beginner the apparatus may 
all be new, a little care and close observation will en- 
able him to become familiar with its operation. The 
student should be held responsible for all apparatus, 
both large and small, which is placed in his charge 
and should see that small apparatus issued to him 
is returned immediately after the test. He should 
always leave such apparatus in good order. 

4. Keeping the Records. — It is important that all 
original data be preserved. To this end, the record of 
observations should be kept on a prepared " Running 
Log" which may be handed in with the report. 
When the Running Log is kept by one man and the 
observations are taken by another, such observations 
should be handed to the log-keeper as soon as taken. 
In some cases it may be found convenient to have a 
number of logs, kept by different men. In such 
cases they should be signed, dated, and handed to 
the principal log-keeper immediately after the test. 

5. Reports. — The reports should be made out in 
ink, except the portion which is made during the con- 
duct of the test. Where one experiment is assigned 
to two or more men, one report, bearing the signature 
of each man, should be handed in. 



INTRODUCTION. 3 

6. Graphic Presentation of Results. — Reports of 
tests intended to show the relation of one variable 
factor to another should generally be accompanied by 
a curve, or set of curves, having the various values of 
the dependent variable as ordinates. The scale chosen 
should be such as to make the curve as large as will go 
on the piotting-paper furnished. It is generally best 
to connect the several points found by a straight line, 
instead of attempting to draw a smooth curve through 
them. The points from which the curve is located 
should be indicated by a suitable sign, and the scale of 
the ordinates and abscissae should be clearly indicated 
on their respective axes of coordinates. It may some- 
times be found desirable to plot several curves on one 
sheet to facilitate comparison. 



CHAPTER II. 
ELEMENTARY MEASUREMENTS. 

7. Measurement of Time. — In the conduct of 
ordinary tests, such as those of engines, boilers, 
pumps, etc., the measurement of time should be made 
with the second-hand of a watch. In order to avoid 
confusion the second-hand should point to zero when 
the minute-hand is on the even minute ; otherwise the 
test might be started with the second-hand at zero 
and end with the minute-hand at zero, thus making 
an incorrect time-reading. In all important tests two 
or more watches should be made to correspond 
exactly, or their difference noted, before the test is 
begun, so that if one watch stops the time-reading 
may not be lost. 

Time-signals. — Signals are usually given by bell or 
whistle. The following is a convenient arrangement: 
thirty seconds before the time for taking observations 
three warning signals are given; ten seconds before 
the time two warning signals are given; and at the 
exact time one signal is given, at which the observa- 
tions are taken. 

Stops. — In case it is necessary to stop an engine-test 
between gongs, note the exact time that the stop is 
made and indicate the same on the Running Log. 
Note the time the engine starts again and ring the 

4 



ELEMENTARY MEASUREMENTS. 



5 



next gong at such a time after the start that the 
elapsed time between the previous gong and the stop, 
plus the elapsed time between the start and the sub- 
sequent gong, shall just equal the ordinary running 
time between gongs. 

8. Measurement of Speed. Speed-counters. — The 
simplest instrument for the measurement of speed is 




6 ENGINEERING LABORATORY PRACTICE. 

the speed-counter, one form of which is shown in 
Fig. i. They are made in many different forms, 
some with one and others with two dials. Those 
provided with rubber tips for contact with the shaft 
are especially recommended. When well made they 
are reliable for speeds as high as two or three 
thousand revolutions per minute. 

9. Revolution-counters. — This instrument, shown 
in Fig. 2, is largely used where special accuracy is 
required or where it is desirable to make a more per- 
manent arrangement for speed measurement. The 
majority of such instruments are not accurate above 
300 or 400 revolutions per minute. 

10. Tachometers. — The tachometer is an instru- 
ment for measuring rate of speed. It is usually per- 
manently connected to the shaft or pulley whose 
speed is to be measured. An instrument of this type 
is the Boyer speed-recorder (Fig. 3), which is exten- 
sively used in railway service. The drum upon which 
the record-paper turns is actuated directly by the 
driving mechanism and moves in proportion to the 
distance passed over or to the number of revolutions. 
The pencil which produces the record is actuated by 
a rotary pump connected with the driving mechanism 
and so constructed as to raise the pencil an amount 
proportional to the rate of speed. The gage, which 
is in cord connection with the pencil-motion, gives a 
visible indication of the rate of speed. Fig. 3^ is a 
detail view of the drum mechanism. 

11. Measurement of Areas. The Polar Planim- 
eter. — The planimeter is an instrument for finding 
the area of any plane figure. The form in common 
use was invented by Amsler and exhibited by him at 



ELEMENTARY MEASUREMENTS. 




Fig. 2.— Crosby Revolution-counter. 




Fig. 3. — Boyer Railway Speed-recorder. 



8 



ENGINEERING LABORATORY PRACTICE. 



the Paris Exhibition in 1867. It consists of an arm 
EP (Fig. 4) to which is pivoted a second arm EF 




Fig. 3a. — Details of Mechanism. 

carrying a record-wheel D and a tracing-point F. 
When in use the point P is fixed and the point F is 




Fig. 4. — Polar Planimeter. 

moved by hand around the outline of the figure whose 
area is desired, in the direction of the hands of a 
watch. The rotation of the record-wheel D is propor- 
tional to the area circumscribed, which is shown by 



ELEMENTARY MEASUREMENTS. 9 

the graduations on the wheel to a given scale. The 
wheel may lie at D or on an extension of the arm 
EF, beyond the point E, the mathematical conditions 
being the same in either case. For the purpose of 
the following demonstration the position of the wheel 
will be assumed to be on the arm EF extended. 
12. Theory of the Polar Planimeter.* 
Let r = oc (Fig. 5) ; 

r' = ob = radius of zero-circle ; 
m = og = og' = og" ; 
n = hg= tig' == h"g" = pi\ 
L = cg=c'g' = c"g"; 
j3 = angle ogc = opy = og r c' ; 
dd = angle coc f = gog ! = cac'. 
The values of r f , m y n y and L are constant for any 
given setting of the instrument. 

The zero-circle of the polar planimeter may be 
defined as the circle generated about the pole-point 
as a center, which when traced by the instrument 
will cause no movement of the record-wheel. In any 
irregularly shaped figure through which the zero-circle 
passes, the differential area (dA) may be taken as that 
portion of the figure outside the zero-circle and 
between two radial lines separated by the angle dd. 
That is, 

dA = bcc'e. 

By subtracting the triangle oeb from the triangle occ' 
we have 

dA = bcc'e = occ' — oeb. 

* The theory of the planimeter which is given herewith has 
been adapted from Carpenter's " Experimental Engineering" by 
C. H. Robertson, M.E., Instructor in Engineering Laboratory, 
Purdue University. 



10 ENGINEERING LABORATORY PRACTICE. 

But 

r r r*d8 
triangle occ r = cc' X — = rdO X — = « 

& 2 2 2 




Fig. 5. 



In the same manner 



triangle oeb = 



r'Vfl 

2 ; 



therefore 



rV0 r' *d0 r* - r" 

ak4 = = — — - 

22 2 



<#. . . (1) 



ELEMENTARY MEASUREMENTS. II 

In tracing the area bcc'e the record-wheel movement 
for be is equal and opposite to that for c'e\ eb, being 
on the zero-circle, causes no movement, and hence in 
tracing the area dA the only effective movement of 
the record-wheel is that for the side ee f . For this 
infinitesimal area the side cc r may be taken as the arc 
of a circle, in the tracing of which the angle ogc (= 0) 
remains constant. The path of the record-wheel will 
be hh'. The component of hh' which turns the record- 
wheel is shown geometrically by wv, drawn perpen- 
dicular to the bisector of the angle cad and midway 
on hh'. It may be considered as an arc of a circle 
about a as a center. While the tracer moves through 
the infinitely small distance ee' the corresponding 
differential record will be 

dR = wv = ai X dd. 
But 

ai = ap — ip = m cos fi — n ; 

therefore 

dR = (m cos j3 — n)dd (2) 

Now in the triangle ogc 

(pc) % = (ogY + (eg) 2 + (log XgeX cos /J), 
or 

r a = m* + V -f 2mL cos /? (3) 

In the triangle oh"c n the tracing-point c ,r is on 
the zero-circle and the plane of the record-wheel is 
radial ; hence c"h" is a right triangle and 

{oc"y = {c"g"+ g "h"f + x\ 



12 ENGINEERING LABORATORY PRACTICE. 

or 

r" = (L + ny + x\ 
But 

x* = m % — « a ; 
therefore 

r' a = V + 2Z^ + ;*' + ^ a - rc a 

= U + m x -\-2Ln (4) 

Subtracting (4) from (3), we have 

r a — r /a = 2Z;# cos /3 — 2Ln, 



or 

= Z(/# cos f3 — n) (5) 



2 
Combining (5) and (1), we obtain 

dA = Z(*« cos /? — n)dO. ... (6) 

Now, substituting the value of dd as found in equa- 
tion (2), we obtain 

dA = LdR. 

Hence, integrating between the limits o and R, we 
have, since Z is constant, 

dA = Lf*dR\ 
A=LR. ...... (7) 

It is seen from equation (7) that the area is equal 
to the length of the arm from pivot to tracing-point, 
multiplied by the distance corresponding to the revo- 
lution of the record-wheel, and is independent of the 
other dimensions of the instrument. 



ELEMENTARY MEASUREMENTS. 1 3 

It can readily be proven that the above demonstra- 
tion is true for areas not adjacent to the zero-circle or 
partly inside and out. 

13. Area of the Zero-circle. — In case the exact 
area of the zero-circle is not known the following 
method may be employed to determine it: With a 
pair of compasses draw arcs of two concentric circles 
the radius of each of which is known to be greater than 
that of the zero-circle. For convenience let the arcs 
subtend an angle of 90 . Place the fixed pole of the 
planimeter at the center of the arcs, and with the 
tracing-point trace successively the periphery of the 
two arcs between their limiting radii, noting the re- 
spective readings on the record-wheel. Let the areas 
of the two sectors be a and a\ and the corresponding 
readings of the record-wheel be R and R\ Let the 
radius of the zero-circle be r'. Then, since the read- 
ing of the record-wheel is equal to the area outside of 
the zero-circle, we have 

a=-r' 2 + R and a' = -r" + R' f 
4 4 

and adding, we obtain 

-r ,a = a + a' - (R + R f ). ..... (8) 

14. Adjustable Planimeter. — From equation (7) 
it will be seen that the area corresponding to one 
complete revolution of the record-wheel is equal to the 
length of the arm L multiplied by the circumference 
of the wheel, the unit of measurement being uniform. 
For instance, if the arm L is 5 inches long and the 
record-wheel has a circumference of 2 inches, one 
complete revolution will signify 10 square inches, and, 



14 ENGINEERING LABORATORY PRACTICE. 

since the wheel is divided into ioo parts and a vernier 
is provided, the instrument will read to hundredths of 
a square inch. Now if the length of the arm L be 
changed to 0.775 inch, one revolution of the wheel 
will correspond to 1.55 square inches or 10 square cen- 
timeters and the instrument will read to hundredths of 
a square centimeter. Hence by changing the length 
of arm L the scale of the instrument can be changed. 
The ordinary form of instrument in use has a fixed 
arm and reads to hundredths of a square inch. An 
instrument is made, however, with an adjustable arm 
(Fig. 6). It may be made to read in different units, 




Fig. 6. — Adjustable Polar Planimeter. 

and can be set to read the M.E.P. of an indicator- 
diagram as follows: 

Calling / the height of the mean ordinate of the 
diagram and / the length of the diagram, then we have 
the area 

A =pl. 

From equation (7) we have 

A=LR; 
whence 

and 

k t 

l~ K 



ELEMENTARY MEASUREMENTS. 1 5 

Now since the arm L is adjustable, we can make it 
equal to the length of the diagram /. We will then 
have /, the height of the mean ordinate, equal to the 
reading of the record-wheel, to the proper scale. 

15. Directions for Use. — i. Handle the instrument 
with care, as it is liable to injury. 

2. Wipe it off carefully before and after using. 

3. See that the wheel revolves freely and the re- 
cording edge is smooth and bright. 

4. Place the diagram to be evaluated on a smooth, 
level drawing-board, having first covered the latter 
with a sheet of smooth calendered paper. Fasten 
with thumb-tacks or pins. 

5. Place the pole-point in such a position that when 
the tracing-point is near the geometrical center of the 
figure the two arms are approximately at right angles. 

6. Trace in the direction of the hands of a watch. 

16. Planimeter Exercise (a). — Read the theory of 
the planimeter (Sections 12 and 13) carefully. 

Find the area of the zero-circle by the method ex- 
plained in Section 13. 

Find the average error of the instrument as follows : 
Draw carefully three rectangles an inch square. Go 
over each several times and find the mean error of 
the instrument. Repeat with three figures of four 
square inches each. In the Report, give make and 
number of instrument, area of zero-circle, and aver- 
age per cent of error, including all readings and cal- 
culations made. Keep a record of results for use in 
the next experiment. 

17. Planimeter Exercise {b). — Find the areas of 
figures on the blank furnished. 

The diameter of the record-wheel is inches. 



l6 ENGINEERING LABORATORY PRACTICE. 

Compute the length of arm Z, using one revolution of 
the wheel as a basis of computation. 

The arm m is inches in length. Compute 

length of arm n. 

In the Report give areas found ; also above dimen- 
sions, with formulae used and calculations in full. 

18. Lineal Measurements. Micrometer Caliper. 
— This instrument is used for outside measurements 
only. The micrometer-screw has forty threads to the 
inch ; hence each revolution will advance it one fortieth 
(= 0.025) of an inch. The band surrounding the 
screw is divided into 25 parts, which allows the move- 
ment to be read to thousandths (^p) of an inch. The 

object to be measured is held between the measuring- 
points and the knurled handle turned until lightly 
touching the piece. Care should be taken not to 
exert too great a pressure, as this will strain the in- 
strument and vitiate the result. Take care to secure 
the same degree of pressure in all cases. 

19. Vernier Caliper. — This instrument is used for 
both outside and inside measurement. For the former 
the scale is graduated in fortieths of an inch and the 
vernier reads to thousandths. In using the vernier 
read first the position of the zero-mark on the vernier 
relative to the scale. This will give tenths and quar- 
ters of tenths. Then by reading the number of the 
mark on the vernier nearest opposite a mark on the 
scale, that number, in thousandths of an inch, is added 
to the reading previously obtained to give the desired 
result. For example, suppose the zero-mark on the 
vernier to read three inches, four tenths and three 
spaces 



ELEMENTARY MEASUREMENTS. 17 

=5 3.0 + 0.4 + (3 times j\ or 3 times 0.025 or °-°75) 
= 3.475. 

Then if mark number 1 1 on the vernier is nearest 
opposite a mark on the scale the complete reading is 

3.475 + .011 = 3.486. 

For inside measurement add 0.25 of an inch to the 
vernier-reading. Never bring the jaws together while 
the piece to be measured is between them. If the 
distance is too great, remove the piece, decrease the 
distance, and apply again until the caliper will just slide 
over the surfaces to be measured. Great care should 
be taken not to strain the instrument by forcing it 
onto the piece. It is very delicately made and should 
be handled with care. 

20. Sweet's Measuring-machine. — This machine 
is a micrometer caliper having a greater range than the 
one previously described. The micrometer-screw has 
a range of one inch, but the tail-piece may be set at 
distances of even inches from the zero position of the 
screw by means of distance-pieces. The instrument is 
furnished with a scale, graduated on its upper edge to 
read in sixteenths of an inch and on its lower edge to 
decimals of an inch. 

The graduated disk has two sets of graduations, that 
on the left corresponding to the upper scale and that 
on the right to the lower. The latter is read in the 
same manner as an ordinary micrometer, reading to 
thousandths directly. The former reads in binary 
fractions, the space between five figures corresponding 
to one thirty-second. The numbers are arranged as 
shown in Fig. 7. Beginning at o and following the 
line of chords to the right, the numbers are in regular 



18 ENGINEERING LABORATORY PRACTICE. 

order, every fifth one being counted. Five complete 
revolutions corresponding to half the travel of the 
screw, or one half an inch, are necessary to pass the 
16 divisions, thus making each division (= five spaces) 
correspond to one thirty-second of an inch. Since 
there are 40 small divisions between the successive 




8 
Fig. 7. 

numbers (as between 1 and 2), any desired fraction 

of a thirty-second can readily be obtained. 

The following is a portion of the directions accom- 
panying the instrument : 

" To measure objects larger than an inch bring the 
index-bar to zero, insert the proper distance-piece, and 
clamp the tail-spindle. Next bring the screw to exact 
contact with distance-piece, turning the latter to be 
sure it is held squarely between the measuring-points. 
When the friction slips leave the distance-piece held 
between the points while you see that the index-bar 
is adjusted as above; then proceed with the measure- 
ment. 

" The index-bar has been carefully set to correct 
the inaccuracy in the pitch of the screw. Do not 
alter it because it seems to give contrary readings. 
A little difference of temperature or an atom of grit 
will make noticeable change in the readings. 



ELEMENTARY MEASUREMENTS. 



19 



" The graduations of the circle upon the right of 
the central line indicate thousandths, and are read in 
connection with the scale upon the front edge of the 
index-bar. Those upon the left are numbered by 
thirty-seconds and the scale upon the back edge of the 
index-bar is used as a ' finder/ To set the machine 
at any desired thirty-second bring the central or ' read- 
ing line ' as near the place as can be done by means 
of the scale upon the index-bar. The number in- 
dicating the thirty-second will then be found near at 
hand. Bring this to the front edge of the bar. In 
measuring binary fractions of thirty-seconds always 
remember that upon this scale it requires five marks 
to count one." 

21. Exercise with Measuring-instruments. — 
Read Sections 18, 19, and 20 on micrometer and 
vernier calipers. 

Measure the five pieces shown in Fig. 8 and make 
Report as indicated in the following blank form : 
REPORT ON MICROMETER AND VERNIER EXERCISE. 



Observer 








Date 


Measured with 
Micrometer. 


Vernier. 


Sweet's Micrometer. 


No. 1 A = 


No 


I 


C = 


No. 1 B = 


" 2C = 


1 1 


2 


B = 


" 2 A = 


" 3 A = 


<< 


3 


D = 


■• 3 c = 


" 3 B = 


< < 


3 


D r = 


"4D = 


" 5 E = 


« 1 


4 


A = 


"4E = 


" 5 F = 


1 1 


4 


B = 


" 5 L = 


" 5G = 


< 1 


4 


C = 




■• 5H = 


< 1 


5 


A = 




" 5K = 


11 


5 


B = 






u 


5 


C = 


• 




1 


5 


D = 






c< 


5 


J = 




No. 4 F = 











20 ENGINEERING LABORATORY PRACTICE. 



No. i. < 



No. 



>D 



No. 3. 



No. 



4- 



^-e— > 





1 



O 



F= Taper per inch 



m 




\\ 


1 


1 


1 



r3fc 



-B >*-C 



No. 5. 



Fig. 8. 



CHAPTER III. 
MEASUREMENT OF LIQUIDS. 

22. Methods of Measuring Water. — The accurate 
measurement of large quantities of water is an im- 
portant factor in the testing of hydraulic and steam 
machinery. The methods of measurement in common 
use may be briefly summarized as follows: By the use 
of 

i. Weighing-barrels or tanks. 

2. Orifices and nozzles. 

3. Weirs. 

4. Meters. 

The use of weighing-barrels in this connection does 
not warrant description here. 

23. Formulae for Flow of Water through an Ori- 
fice. — The theoretical velocity of water flowing under 
any head is the same as the velocity attained by fall- 
ing through a distance equal to that head. If the 
head be represented by H and the resulting velocity 
by V y then 



V=V2gH. (1) 

Now if the issuing stream were of the same cross- 
sectional area as the orifice and flowed with the 
velocity due to its head, the rate of flow would be 
represented by the formula 



Q = FV2g-H, (2) 

21 



22 ENGINEERING LABORATORY PRACTICEc 

where Q is the rate of discharge in cubic feet per 
second, and F is the area of the orifice in square feet. 
With an orifice in a thin plate the conditions men- 
tioned above do not exist. The velocity of discharge 
is less than the theoretical velocity and the area of the 
stream is less than that of the orifice. It becomes 
necessary, then, to introduce into formula (2) a 
coefficient C y representing the ratio of the actual flow 
to the theoretical. The formula then becomes 



Q=CFV2gH. .... (3) 

24. Determination of Coefficient of Discharge of 
an Orifice in a Thin Plate. — The coefficient C in 
formula (3), Section 23, is determined by experiment. 
It varies slightly with the form of the orifice and with 
the head. The apparatus required to make such a 
determination includes a suitably arranged stand-pipe 
to which the orifice may be attached and in which a 
given head of water can be maintained, and a cali- 
brated tank to receive the stream of water discharged. 
The quantity of water discharged in a given time 
under a given head may thus be measured directly and 
the coefficient computed by means of the formula. 

Specific Directions. — Run tests under six different 
heads, as may be specified by the instructor. Prepare 
Running Log and post observers in accordance with 
the following schedule of observations: — 

1. Log and time — In charge. 

2. Weight of water, 

3. Head. 

Start the pump which supplies the stand-pipe, giv- 
ing attention to the lubricator and the cylinder-cocks. 



MEASUREMENT OF LIQUIDS. 



23 



Regulate the head of water in the stand-pipe by the 
pump-throttle. The length of each test is governed 
by the capacity of the tank into which the issuing 
stream is directed, and readings of time and quantity 
of water discharged should be taken at regular inter- 
vals of such a length that at least six (6) readings may 
be secured under each head. 

When the desired head has been secured, close the 
tank discharge-valve and note time. Take readings 
as explained above until the capacity of the tank is 
reached. Discharge the tank, change the head, and 
repeat. In case the several readings for any head do 
not show a steady flow, repeat the test under that 
head. 

The Report should be made out on the form shown 
below, and should be accompanied by the Running 
Log. 

25. Form. 

FLOW OF WATER 



THROUGH A, 



Observers X 



Form of Orifice or Nozzle 
(Sketch). 



FORMULA. 



Date, 



Diameter, feet. 
Area, sq. feet. 



Number 

of 
Experi- 
ment. 


Head 

in 
Feet. 


Time 

in 

Seconds. 


Cubic 
Feet. 
Total. 


Cubic 

Feet 

per 

Second. 


Co- 
efficient of 
Dis- 
charge. 


Notes. 
















Average. 















24 ENGINEERING LABORATORY PRACTICE. 

26. Calibration of an Orifice. — Orifices of various 
forms are often used to measure a constant flow of 
water. It is convenient in such cases to calibrate 
them, i.e., to determine the rate of discharge under 
different heads. For this purpose the issuing stream 
is directed into a weighing-barrel, while the head is 
kept constant, and the quantity of water discharged 
per second is noted. These results, obtained under 
different heads, are plotted in the form of a curve. 

Specific Directions. — Run tests under six different 
heads as may be specified by the instructor. Proceed 
as follows: Prepare the Running Log. Drain the 
weighing-barrel and start the flow of water, carefully 
regulating the same to secure the desired head. Set 
the poise on the platform-scale to read twenty (20) 
pounds in excess of the weight of the barrel when the 
stream is flowing and the discharge-valve is open. 
Begin the test by closing the discharge-valve and 
noting the time when the beam rises and the poise 
reading. Set the poise to read a little under the full 
weight of the barrel, and when the beam rises again 
note the time and the poise reading. The barrel may 
now be emptied, the head changed, and a new test 
begun. 

During each test keep the head constant by regulat- 
ing the supply-valve. 

The Report should be made out in accordance with 
the form shown below, and should be accompanied by 
a curve, carefully plotted on cross-section paper, using 
the various heads as abscissae and the flow in cubic feet 
per second as ordinates. 



MEASUREMENT OF LIQUIDS. 



25 



27. Form. 



FLOW OF WATER 



THROUGH A 



Observers < 



Form of Orifice or Nozzle 
(Sketch). 



Date 



Diameter, feet. 
Area, sq. feet.. 



Number 

of 
Experi- 
ment. 



Head 

in 
Feet. 



Time 

in 

Seconds. 



Pounds, 
Total. 



Pounds 
per 

Second. 



Cubic 

Feet 

per 

Second. 



Notes. 



28. Determination of the Coefficient of Discharge 
of a Nozzle. — The rate of discharge from a properly 
designed nozzle approaches closely the theoretical 
rate. If the proper internal curvature of the nozzle 
is secured, there is no contraction of the area of the 
jet beyond the tip of the nozzle. The velocity of the 
jet is, however, reduced below the theoretical by fric- 
tion, and a coefficient must be introduced in formula 
(3), Section 23, to give the actual rate of discharge. 
To determine the value of the coefficient for a given 
nozzle under different heads proceed as explained 
under the " Specific Directions,' ' Section 24. 

29. Formulae for Flow of Water over Weirs — 
The rate of flow of water over a rectangular overfall 
weir with complete and perfect contraction is given 
by Francis' formula as follows: 



Q = \CH\b-o.\nH))/2g, 



26 ENGINEERING LABORATORY PRACTICE. 

where Q = flow in cubic feet per second; 

H = head in feet over weir from crest to surface 
of still water back of weir; 
b = breadth in feet at water-level; 
n = number of contractions, i.e., area of 
channel back of weir divided by area of 
wetted perimeter; 
C = a coefficient of discharge. 
In Section 186 is given a table of the value of the 
coefficient C for different heads and breadths. 

The formula for flow over a triangular overfall weir 
is 

30. Measurement of Head. — Measurements of the 
head of water over a weir are usually made with 
a hook-gage. This instrument is placed on the 
up-stream side of the weir and a sufficient distance 
from it to avoid the effects of the surface-curve near 
the weir. It consists of a metal hook with a fine, 
sharp point, which may be raised or lowered to the 
level of the water and readings made of its position 
by a suitable scale. To take a reading the hook is 
lowered until the point is below the surface; it is 
then raised until the point just pierces the surface 
and a reading of the scale made. This reading when 
compared with that when the hook-point is level 
with the crest of the weir, called the zero-reading, 
will give the head over the weir. 

The zero-reading may be determined in several 
ways. In some cases it may be done with a spirit- 
level and straight-edge. Where this method cannot 
be used, a small quantity of water is allowed to flow 



MEASUREMENT OF LIQUIDS. 27 

over the weir and the hook-gage read, at the same 
time measuring the depth of water over the crest with 
a thin and finely graduated scale. The hook is then 
lowered by the amount measured. Another method 
is to grease the edge of the weir and let the water 
stand as near the level of the crest as possible, then 
read the gage. 

31. Water-meters. — Water-meters are liable to 
error from many sources and should therefore always 
be calibrated under the conditions with which they are 
to be used before their readings can safely be relied 
upon for experimental purposes. Among the many 
sources of error may be named change in temperature 
and head, the presence of dirt or air in the water, and 
the constant errors of calibration. 

32. Calibration of Water-meters. — The calibrat- 
ing of a water-meter could be easily done if the per 
cent of error were constant for all rates of flow. Since 
this is not the case, it becomes necessary to calibrate 
for different rates. This may be accomplished with 
the aid of a tank of sufficient size, graduated in cubic 
feet. A pressure-gage should be placed in the supply- 
pipe between the meter and the valve, to register the 
head. Three observers are necessary for the work: 
one to take the meter-reading, one to take that on the 
tank, and the third to keep log and time. The opera- 
tion is as follows: Open the supply- and discharge- 
valves and allow the water to flow for a few minutes 
until the rate of flow, as shown on the pressure-gage, 
becomes steady; then close the discharge-valve, and 
as soon as water appears in the gage-glass on the tank, 
at a signal from the time-keeper, take simultaneous 
readings of the meter and tank. Repeat the readings 



28 ENGINEERING LABORATORY PRACTICE. 

every minute until the tank is full. Empty the tank. 
Throttle the admission-valve a little so as to change 
the rate of flow and repeat. Make experiments at six 
different rates or pressures. The observations should 
be recorded on a Running Log, which should be made 
out to cover the following: 

1. Time. 

2. Pressure. 

3. Tank-reading. 

4. Temperature. 

The Report should be made out in the form shown 
below and should be accompanied by the original 
Running Log. 

33. Form. 

REPORT ON CALIBRATION-TEST 

OF WATER-METER. 



Observers \ Date 



a. Number of test 

b. Duration of test, minutes 

c. Pressure of head, average 

d. Temperature of water, average 

e. Rate of discharge per minute by meter 

f. Rate of discharge per minute by tank 

g. Total volume by meter 

h. Total volume by tank 

1. Total excess or deficiency in meter reading 
/. Per cent of error (-[- or — ) 



CHAPTER IV. 



MEASUREMENT OF GASES. 



34. Methods. — The flow of gases may be measured 
by the following methods: 

1. By flow through an orifice. 

2. By determination of velocity. 

3. By some form of meter. 

35. Flow through an Orifice. — Where the flow of 
gas is at a constant rate, an orifice may be con- 
veniently employed in determining the rate of flow. 
Fig. 9 shows the arrangement of an orifice for this 



Fig. 9. — Arrangement of Orifice. 

purpose. At /, and / a are U-tubes for measuring 
the pressure before and after passing the orifice, and 
at t x is a thermometer for measuring the initial tem- 
perature. 

36. Formula for Flow of Air through an Orifice. 
— The flow of air through an orifice can be computed 

29 



30 ENGINEERING LABORATORY PRACTICE. 

with the aid of the following, called Fliegner's 
formula:* 

P 
G = o.$2,oF^L=, when p x > 2p a ; 



G=i.o6oFJ Pa{p \ r A) when A<*Ai 

where /, is the absolute pressure in the reservoir, p a is 
the atmospheric pressure, T x is the absolute tempera- 
ture of the air in the reservoir in degrees Fahrenheit, 
G is the flow in pounds per second, and F the area of 
the orifice in square inches. 

37. Formula for Flow of Steam through an Ori- 
fice. — The flow of steam through an orifice may be 
calculated by the following, called Napier's formula :f 

G=zF jo when A = <> r >lA; 

G = F 42 I 2 Pa \ WhCn A < 1A. 

The nomenclature is the same as in Fliegner's 
formula, just preceding. 

38. Experiments on Flow of Steam. — The pur- 
pose of these experiments is to verify existing formulae 
for the flow of steam and to determine the change in 
the rate of flow under different conditions of pressure 
and moisture. The apparatus consists of an orifice of 
suitable dimensions (see Fig. 10) provided with gages, 
a condenser for measuring the steam, and two calorim- 

* See Peabody's "Thermodynamics," page 135. 
f Ibid., page 140. 



MEASUREMENT OF GASES. 



31 



eters for ascertaining the quality of the steam. The 
apparatus also includes a water-jacket for regulating 
the moisture of the inflowing steam to suit the desired 
conditions. 

Specific Directions, — To determine the change of 
rate of flow with change in the ratio of final to initial 
pressure, run a series of five tests with constant initial 




Fig. 10. 



and variable final pressure. The conditions should be 
as follows: 

For the first test, final pressure as low as obtainable. 

For the second test, final pressure to be 0.3 of 
difference between initial and atmosphere. 

For the third test, final pressure to be 0.5 of differ- 
ence between initial and atmosphere. 

For the fourth test, final pressure to be 0.7 of differ- 
ence between initial and atmosphere. 

For the fifth test, final pressure to be 0.9 of differ- 
ence between initial and atmosphere. 

Cooling-jacket to be cut out. 

Each test should be of 15 to 20 minutes duration, 
the conditions of the test to exist for five minutes 
before the first observation is taken. 

The following observations should be taken every 
two minutes: initial, intermediate, and final pressure. 
The following should be taken every four minutes: 
pressure and temperature in each calorimeter. The 



32 ENGINEERING LABORATORY PRACTICE. 

weight of condensed steam should be taken once for 
the test, and the barometer read twice during the test. 
Use only enough cooling water on the condenser to 
condense the steam. Be sure that the pressure-gages 
are not subjected to a pressure beyond their range. 
The Report should include: 
i. Sketch and description of apparatus. 

2. Sketch and dimensions of orifice. 

3. Tabulated statement of results for each test. 

4. A curve having ratio of final absolute pressure 
to initial absolute pressure for abscissae and flow of 
steam in pounds per hour for ordinates. 

In order to determine the effects of different per- 
centages of moisture in the steam repeat the above 
series, manipulating the cooling-jacket to secure in- 
creasing amounts of moisture in the steam. 

39. Method by Determination of Velocities. — 
This method has a limited application, but may some- 
times be found convenient to employ. It involves 
the use of an instrument for determining the velocity 
of flow, such as an anemometer or Pitot tube. The 
velocity, thus determined, in connection with the 
cross-sectional area of the pipe or conduit, gives the 
rate of flow. 



CHAPTER V. 
MEASUREMENT OF PRESSURE. 

40. Pressure-gages. — The most common instru- 
ment for the measurement of pressures in excess of a 
few pounds is the Bourdon gage (Fig. 11), which con- 
sists essentially of a curved tube, oval in cross-section, 




Fig. 11. — Bourdon Gage, 

having one end closed and the other in communication 
with the pressure to be measured. The tendency of 
an internal pressure is to make the cross-section round 
and thus straighten the tube. The motion produced 
serves to rotate a pointer by an amount proportional 
to the pressure. Such instruments may be used for 
pressures of either liquids or gases provided they are 

33 



34 ENGINEERING LABORATORY PRACTICE. 

not heated above 12 5 or 150 F., as excessive tem- 
perature will lengthen the levers and draw the spring 
temper of the tube. When used for steam-pressure, 
a siphon or trap should be used to prevent the steam 
from entering the gage. 

When making a selection of such a gage to measure 
a given pressure, it should be borne in mind that, since 
these gages are apt to be inaccurate at the lower 
points of their travel, the lowest total range should be 
chosen which is compatible with the pressure to be 
measured. 

41. Vacuum-gages. — Bourdon gages of special 
design are used for the measurement of vacuo, 
movement of the pointer being obtained by means 
similar to that described for pressure-gages. They 
are generally graduated to read in inches of mercury 
below atmospheric pressure. 

42. Calibration of Gages. — Method by Comparison 
with Standard. — In order to test the accuracy of 
pressure-gages they should be calibrated by being 
subjected to known pressures within their range and 
their error noted. In the method by comparison 
with standard the gage to be tested is placed in pipe- 
connection with a standard gage of known error and 
both subjected to pressure. This pressure may be of 
water, oil, or steam. If either oil or water be used, 
the pressure may be secured by a steam- or hand- 
pump. The difference between the readings of the 
two gages may then be noted and a table of correc- 
tions made for the gage under test. 

Specific Directions. — Before making the test see that 
the pump-lubricatcr is filled and started. Start the 
pump slowly and gradually increase its speed until the 



MEASUREMENT OF PRESSURE. 



35 



maximum pressure, depending upon the available 
steam-pressure, is reached. Stop the pump and read 
the gages. Allow the pressure to decrease by even 
five-pound steps as shown on the standard gage by 
manipulation of the outlet-valve. Take simultaneous 
readings of both gages at each pressure and enter the 
same on the form shown below. Check all readings 
once by repeating the test. 

In preparing the Report enter in the column 
headed " Actual Pressure " the corrected reading of 
the standard gage. The corrections, if there are 
such, will be found posted near the gage. In the 
column of ic Corrections ' enter the difference be- 
tween the corrected reading of the standard gage and 
the reading of the gage under test. These differences 
should be preceded by the minus or plus sign, accord- 
ing as the gage under test reads above or below the 
standard gage. 

43. Form for 



CALIBRATION OF STEAM-GAGE 

BY COMPARISON WITH 

Make and number of gage 

Observer Date. . . 



Standard 
Gage. 


6 
u 

3 

CO 

en 

CD 

u 

Ph 

S3 

< 


CD 

a 
O 

O 
fa* 

G 

•3 

CD 


+ 

u 



1 *a 

<s CD 
I? 

u v 

cdX> 

u, O 

— 
U 


Standard 
Gage. 


cd' 
u 
3 
en 
en 
CD 
Ih 

3 

CD 

< 


CD* 

tfl 



O 

he 

•3 

CD 


B 



1 "O 

wCD 

J 15 

U CD 
CD.O 

*-> -* 

u O 

*-» 

u 




en 

•a 

a 
3 

& 


a 


CD 
U 
U 

O 

V 


en 

C 
3 
O 
PL. 


d 





CD 

u 

u 



u 


Remarks. 

























36 



ENGINEERING LABORATORY PRACTICE. 



44. Calibration of Gages. — Method by Comparison 
with Crosby Gage-tester. — Gages may be calibrated by 
subjecting them to liquid pressure, the same pressure 
being made to sustain weights of known amount. 
The apparatus, shown in Fig. 12, consists of a cham- 
ber filled with oil, to which the gage is attached and 




Fig. 12. — Crosby Gage-tester. 

which terminates in a cylinder having a nicely fitting 
piston of one fifth of a square inch cross-sectional area. 
The piston is furnished at its upper end with a plat- 
form upon which accurate weights may be placed. 
The piston and platform together weigh one pound, 
and require therefore a pressure of five pounds per 
square inch (acting on the piston-area of \ of a square 
inch) to sustain them. In communication with the 
oil-chamber referred to is a reservoir fitted with an 
adjusting plunger which is operated by the hand- 
wheel shown on the right. This is used to force oil 
into the system as occasion demands in order to keep 
the platform and weights floating. 



MEASUREMENT OF PRESSURE. 37 

Specific Directions. — Open the cock connecting the 
gage with the oil-cylinder and screw in the plunger 
until the piston and platform have risen two or three 
inches above the lowest position. Twirl the platform 
to avoid a false reading due to piston friction, and take 
a reading of the gage, recording the same, together 
with the actual pressure (five pounds), in the proper 
columns on the form shown above. Add successive 
weights by five-pound steps and take corresponding 
readings, twirling the platform each time while taking 
the reading. Continue up to the limit of the gage 
and repeat, to check the results. 

In preparing the Report, leave the columns headed 
li Standard Gage " blank. In the column of " Correc- 
tions " enter the difference between the actual pres- 
sure and the reading of the gage under test. These 
differences should be preceded by the minus or plus 
sign, according as the gage-reading is greater or less 
than the actual pressure. 

45. Correction of Gages. — If an error appears as a 
result of calibration it may generally be corrected. 
If the error is a constant one, the hand may be 
removed with a needle-jack and moved an amount 
corresponding to the error. If the error is an increas- 
ing or diminishing one, it can be corrected by chang- 
ing the length of the levers which operate the pointer. 
It is generally desirable to set the gage to read cor- 
rectly at the pressure under which it will be most fre- 
quently used, especially if it is to register a constant 
pressure, as that of a boiler. In such a case, the gage 
should be subjected to the desired pressure and the 
needle placed to indicate the same on the dial. 

46. Manometers. — For the measurement of small 



38 



ENGINEERING LABORATORY PRACTICE. 



pressures or vacuo the U-tube manometer is in com- 
mon use. It consists usually of a U-shaped tube of 
glass, partially filled with mercury or water and pro- 




Fig. 13. — Bristol Recording Pressure-gage. 

vided with a scale for reading the difference of level 
of the liquid in the two legs. One branch of the tube 
is connected with the pressure or vacuum to be 
measured, and the other is open to the atmosphere. 



MEASUREMENT OF PRESSURE. 39 

The difference of level of the liquid in the two 
branches, measured in inches, multiplied by the 
weight of a cubic inch of the liquid gives the pressure 
in pounds per square inch above or below atmos- 
phere.* In reading the height of mercury columns, 
read the level at the top of the meniscus or con- 
vexity; in reading a water-column, read the bottom 
of the meniscus. 

47. Bristol Recording-gage. — This gage, one form 
of which is shown in Fig. 13, is so arranged that the 
pressure or vacuum actuates a pen which leaves a 
continuous record on a revolving disk of paper. The 
disk is operated by clockwork. The instrument is of 
special value in recording the fluctuation of pressures 
subject to considerable variation. It is a valuable 
adjunct in making tests of boilers, the record obtained 
more nearly representing the average pressure than 
is possible with periodic observations. 

* The weight of a cubic inch of mercury at 6o° F. is 0.490 
pounds ; of water at 6o° F. 0.0360 pounds. 



CHAPTER VI. 
MEASUREMENT OF TEMPERATURE. 

48. Mercurial Thermometers. — Measurements of 
temperature are usually made by means of mercurial 
thermometers, which depend for action on the expan- 
sion of mercury in a bulb and capillary tube when 
subjected to heat. 

Mercurial thermometers when used in engineering 
work should frequently be tested for accuracy, as they 
are liable to error from many sources, such as variable 
diameter of bore, permanent change of volume of bulb 
from use, etc. Great care should be exercised in 
handling, to reduce breakage and damage to a mini- 
mum. 

49. Rules for Care of Thermometers. — The fol- 
lowing rules should be observed in connection with 
the use of mercurial thermometers: 

1. Keep the thermometer in its case when not in 
use. 

2. Exercise care in inserting and removing from the 
thermometer-cup. 

3. See that there is no water in the cup before 
inserting thermometer. 

4. Keep the cup filled with heavy oil, and wrap 
the stem with waste at the mouth of the cup to avoid 
contact with the metal. 

40 



MEASUREMENT OF TEMPERATURE. 41 

5. Be sure that the range of the thermometer is 
high enough for the temperature to which it will be 
exposed. 

6. Do not carry the thermometer wrong end up. 

7. Return the thermometer to its own case when 
through using. 

50. Calibration of Thermometers. — Method by 
Comparison with Standard. — In order to test the 
accuracy of thermometers, they should be subjected 
to known temperatures and their errors noted. This 
may be done by comparing their readings with those 
of a standard thermometer whose error is known. 

Specific Directions. — Place the thermometer to be 
calibrated and the standard in adjacent cups of the 
same depth in the testing-drum. Allow steam to run 
through the drum for a few minutes to warm it up, 
then throttle the discharge until a pressure of five 
pounds is maintained upon the gage. Allow the 
mercury in the thermometer to come to rest (five to 
ten minutes) and take simultaneous readings of the 
two thermometers, removing them from their tubes 
only far enough to bring the mercury to view, and 
taking the readings as quickly as possible to avoid the 
cooling effects due to partial removal from the tubes. 
Close the discharge-valve again until the pressure is 
raised to ten pounds, and repeat. Carry the pressure 
by five-pound steps up to the limit of pressure, and 
descend in the same manner. Be sure that time is 
allowed for the mercury to come to rest before reading. 
Read Section 49 before beginning the test. Report 
on the form shown below, omitting the columns headed 
" Steam-gage " and the barometer reading. 



42 



ENGINEERING LABORATORY PRACTICE. 



51. Form for 

CALIBRATION OF THERMOMETER 

BY COMPARISON WITH 

Thermometer checked : 

Distinguishing mark Range of scale . 

Range of test . . . 



Scale 



Observers 



Date 



No. 



Standard 
Thermome- 
ter. 


Steam- 
gage. 


6 

u 

P 

u 
a; 
a 

a 

u 
H 

<u 

H 


Thermome- 
ter 
Tested. 


he 
c 

•3 

0« 


u 

u 
u 

« 

c 


c 


tub 
c 

"■a 

u 


u 



Ih 
Ih 

w 

c 


c 


bi 

.S 

•5 


Correction 
(+ or -) 
to be added. 

















Remarks. 



Barometer : 



52. Calibration of Thermometers. — Method by 
Comparison with Temperature dice to St earn- pressure. — 
The temperature of saturated steam varies with the 
pressure according to a known ratio. If, therefore, 
the pressure be known, the corresponding tempera- 
ture can be ascertained. 

Specific Directions. — Follow the method given in 
Section 50, using only one thermometer, the one 
under test, and noting the reading of the steam-gage 
attached to the drum. After the test, copy the cor- 
rections for the gage from the sheet posted near by 
and find the true pressure. Then by reference to the 
Table of Properties of Saturated Steam, Section 182, 
find the true temperature, after which the error of 



MEASUREMENT OF TEMPERATURE. 43 

the thermometer can readily be found. Note that 
the pressures given in the table are absolute, therefore 
add barometric pressure to the corrected gage-pres- 
sure before referring to the table. As this method 
depends upon the steam being saturated, the water- 
jacket on the steam-pipe should be used if any 
doubt exists as to the condition of the steam. Read 
Section 49 before beginning the test. Report on the 
form shown above, omitting the columns headed 
" Standard Thermometer/' 

53. Rate of Rise and Fall of a Mercurial Ther- 
mometer. — The object of this experiment is to give 
the investigator an idea of the time required for the 
mercury in a thermometer to rise to the height corre- 
sponding to the temperature to which it is exposed. 

Specific Directions. — Three thermometers are neces- 
sary: (a) to give the lowest temperature available, 
which may be the temperature of the atmosphere; 
(J?) to give the highest temperature available as of 
steam under pressure; and (c) the thermometer to be 
experimented upon. 

To determine the rate of rise, (1) let the reading of 
the thermometer c agree as nearly as possible with the 
reading of a; (2) expose c to the highest temperature 
available, and read and record its temperature at in- 
tervals of fifteen seconds until its reading agrees nearly 
or quite with that of b. To determine the rate of fall, 
reverse the process. 

Repeat each experiment, and if the results do not 
agree closely perform the work two or more times. 
Plot the mean results of the two series which most 
nearly agree. No report other than the curve will be 
required. Read Sections 6 and 49. 



44 



ENGINEERING LABORATORY PRACTICE. 



54. Variation of Thermometer-reading with 
Stem-immersion. — The reading which a thermometer 
will give varies somewhat with the length of stem 
exposed to the temperature. To determine that 
variation, two thermometers are needed. They 
should first be placed in tubes of medium length and 
compared at intervals of ten pounds steam-pressure 
for a range of one hundred pounds. One should then 
be assumed as standard and left in the tube, while the 
other is moved to a tube of a different length and 
again compared. It should be again moved and the 
work repeated. The Report should follow the form 
given below. Read Section 49 before beginning the 
test. 

55. Form for Experiment on Stem-immersion. 

REPORT ON VARIATION OF THERMOMETER-READING 
WITH STEM-IMMERSION. 



Observers 



Date. 



Steam-gage. 



C 

■3 



■o.S . 

G u <" 

•a x! w 



Thermometer 
Checked. 



a 



!h 3 



bo . 
c « 






Notes. 



Thermometer checked: 

Designating mark 

Scale ....... — 

Range of scale 

Depth of medium tube inches 

•* ' 4 long tube 

" " short tube " 

No. degrees covered: 

in medium tube 

in long tube. 

in short tube 



MEASUREMENT OF TEMPERATURE. 4$ 

56. Pyrometers. — Copper-ball Calorimeter. — The 
determination of temperature by this method involves 
the use of the following apparatus: a copper ball 
about one inch in diameter and a copper cup provided 
with a non-conducting jacket. The ball is introduced 
into the medium whose temperature it is desired to 
ascertain and left long enough to arrive at the correct 
temperature. It is then transferred quickly to the 
jacketed cup in which is a known weight of water at a 
known temperature. Knowing the weight of the cup 
and ball and their specific heats, the following formula 
can be applied : Let JV l9 W„ and W z be respectively 
the weights of the ball, cup, and water. Let t x be the 
initial and / 2 the final temperature of the water; let T 
be the initial temperature of the ball, and 5 be the 
specific heat of copper. Then 

W X S{J- tj = (w t s+ w$t t - o, 

from which 

1 w x s " 1 " ra - 

57. Le Chatelier Pyrometer. — This instrument 
furnishes a very convenient means of measuring tem- 
peratures up to the melting-point of platinum. It 
consists of a joint of two wires having different 
thermo-electric properties, such as platinum and an 
alloy of platinum and iridium. This joint when heated 
generates an electric current which is proportional to 
the temperature. By using a sensitive mirror-gal- 
vanometer, the current and hence the temperature 
can be ascertained. 



46 ENGINEERING LABORATORY PRACTICE. 

The instrument must be calibrated before it is ready 
for use. This is done by subjecting the joint to 
known temperatures and noting the resultant deflec- 
tions of the galvanometer. From the figures obtained, 
a curve of deflections and temperatures may then be 
plotted. The instrument should be calibrated as 
nearly as possible under the conditions with which it 
is to be used. 



CHAPTER VII. 
CALORIMETERS. 

58. Definition. — The steam-calorimeter is an in- 
strument for determining the amount of moisture con- 
tained in steam. There are several different forms 
which may be roughly classified as follows: 

1. Condensing calorimeters. 

2. Superheating calorimeters. 

3. Separating calorimeters. 

Two of the most convenient and reliable forms are 
the Peabody Throttling Calorimeter, belonging to the 
second classification, and the Carpenter Separating 
Calorimeter, belonging to the third classification. 

59. Peabody Throttling Calorimeter. — This calo- 
rimeter depends for its action upon the property of 
dry steam by which it becomes superheated by 
throttling. 

The calorimeter consists of an orifice a, Fig. 14, in 
communication with a chamber b. The latter is fitted 
with a thermometer c, a pressure-gage d, and an 
exhaust-pipe and valve e. Steam in entering the 
chamber through the orifice is superheated and the 
contained moisture is evaporated into steam. The 
cut shows a convenient form of the instrument, made 
from ordinary pipe fittings. All the parts should be 
carefully and thoroughly covered to reduce radiation. 

47 



4 8 



ENGINEERING LABORATORY PRACTICE. 




^^^^^iL^ 




rvJ C 



edid rereads 



w 

H 

w 

g 

0) P$ 

be O 

H 
H 
C 

w 

H 

I 



g 



F> 



CALORIMETERS. 49 

The formula is derived in the following manner: 
Let 

p x = boiler-pressure, absolute; 
p^ = pressure in calorimeter, absolute; 
t s = temperature in calorimeter; 
r, and q x = heats of vaporization and of the liquid 

corresponding to p x \ 
A, and / 2 = total heat and temperature corresponding 
to / a ; 
C p = specific heat of steam ; 
x x = quality of steam required. 
Then the heat in a pound of steam flowing to the 
orifice will be 

and that in a pound of steam in the chamber b> after 
passing through the orifice, will be, assuming that all 
the moisture is reevaporated, 

K + C/t. - Q. 

Now, assuming that no heat is lost or converted 
into work during the transformation, these two quan- 
tities must be equal. Whence 

*fx + 9i = K + C,(t, - t,), 

. r K + Clt, - /,) - q x 
.. x x - 

60. Limitations of the Throttling Calorimeter. — 
It is apparent, on consideration of the foregoing 
formulae, that if the entering steam contains too great 
a percentage of moisture, it may fail to superheat on 
passing through the orifice. This, then, is the limit- 
ing condition under which the calorimeter can be used. 



50 ENGINEERING LABORATORY PRACTICE. 

The point at which superheating ceases varies ordi- 
narily from about 3 per cent with low steam-pressures 
to 7 per cent at very high pressures. The precise 
limit under any given pressure varies slightly with the 
pressure in the calorimeter. 

61. Use of the Throttling Calorimeter. — Care 
should be taken in placing a calorimeter that a fair 
sample of steam is obtained. To this end the calo- 
rimeter-pipe should extend well into the steam-pipe 
and should be provided with perforations inside the 
steam-pipe. The A. S. M. E. recommends that the 
calorimeter-pipe be \ inch in size, that it extend into 
the steam-pipe to within £ inch of the opposite wall, 
that the inner end be plugged, and that it be provided 
with not less than twenty ^-inch holes distributed 
along and around its length, no hole being closer than 
\ inch to the inner end. The instrument should be 
well wrapped with hair-felt or asbestos, to prevent 
radiation. It should be started at least ten minutes 
before the first observation is to be made, to allow the 
conditions to become settled. A pressure of 4 or 5 
pounds should constantly be maintained by manipulat- 
ing the discharge-valve. The thermometer should 
be put in place after the instrument is started and 
removed at the end of the test. Never close the dis- 
charge-valve without first shutting off the calorimeter- 
gage. The observations to be taken are pressure of 
steam in pipe, pressure and temperature of steam in 
calorimeter, and barometric pressure. The report 
should be kept on the calorimeter form shown below. 

In testing a small boiler the calorimeter may be 
shut off part of the time in order to avoid the waste 
of a large quantity of steam. In making a combined 



CALORIMETERS. 



51 



engine- and boiler-test when the water is measured 
before entering the boiler, the length of time which 
the calorimeter is in action should be carefully noted, 
in order to calculate the weight of steam lost, as ex- 
plained in Section 37. 

62. Form for Calorimeter Test. 

TEST FOR DETERMINING THE QUALITY OF STEAM 

by use of Throttling Calorimeter No 

Tests made in connection with No 

Made by Date 



In 








1 


u 


u 




£} 






3 


<u "tj 


<u 


« C JJ 




B 

be 

c 



a 




G 

u 
u 


05 

u bi 
a. « 


bserved T 
perature c 
Steam. 


ressure in 
Calorimet 
by Gage. 


bserved T 
perature i 
Calorimet 


Notes. 


O 


H 


Q 


CO 


O 


0< 


O 





















Barometric pressure 

Absolute steam-pressure 

Temperature corresponding with steam-pressure 

Absolute pressure in calorimeter 

Temperature corresponding with pressure in calorimeter 

Quality of Steam in 

Per cent of priming 

Degrees superheated 

63. Carpenter Separating Calorimeter. — This in- 
strument: consists of a cylindrical vessel, so constructed 
that all the moisture contained in the steam passing 
through it will be separated and retained, the dry 
steam only passing on to the receiver, where the quan- 
tity collected is indicated by a gage-glass graduated 
in pounds and tenths at a temperature of uo° F. 
The separating vessel is provided with a gage-glass and 
scale graduated in hundredths of a pound, at a tern- 



52 ENGINEERING LABORATORY PRACTICE. 

perature corresponding to steam of ordinary working- 
pressure. The quality of steam is found as follows: 
Suppose the weight of moisture collected in a given 
time, as shown on the scale of the separating-chamber, 
be represented by W, and the weight of dry steam 
collected in the same time by W x . Then the per- 
centage of moisture to the whole quantity is 

W 

y ' ~ w+ w; 

The percentage of dry steam is 



x = I — y =z 



W+ W x 



64. Directions for Use. — In using the instrument, 
allow steam to blow through it until it is thoroughly 
heated, and allow sufficient water to gather in the 
separating-chamber to reach the zero-mark on the 
scale. Fill the condensing-vessel with cold water and 
note carefully the initial level on each glass. The test 
may now be run until the separating-chamber is full. 
The instrument should be well wrapped from the main 
steam-pipe to the elbow connecting with the calorim- 
eter proper. 

65. Barrel Calorimeter. — The barrel calorimeter 
belongs to the first division of the classification given 
above, viz., the condensing calorimeters. It is much 
less accurate than the calorimeters previously de- 
scribed, and, while one of the earliest forms, is now 
but seldom used. It consists usually of a weighing- 
barrel filled with water into which may be directed 
the sample of steam. The steam may be introduced 
through rubber hose or a steam-pipe, the latter 



CALORIMETERS. 53 

method being preferred. When using pipe there 
should be provided a cock opening to atmosphere just 
before the pipe enters the barrel. The lower end of 
the pipe should be fitted with a T, opening horizon- 
tally, and may be drilled with ^--inch holes for some 
distance from the lower end, in order to secure an 
equal rise of temperature throughout the barrel. 

The method of making a determination is as fol- 
lows: Fill the barrel with water and turn on steam 
until the temperature of the water has risen to about 
150 F. This is to heat the barrel and reduce the 
error due to its cooling effect. Drain the barrel. 
Now refill the barrel, open the air-cock so that the 
water-level in the pipe may be the same as that in 
the barrel and weigh. Take a reading of the tem- 
perature. Close the air-cock and turn on the steam e 
When the temperature has risen to about 12 5 F., 
turn off steam, open the air-cock, and again weigh. 
The quality of the steam may now be calculated from 
the formula derived as follows: 

Let x x = quality of steam; 

t 3 = initial temperature of water; 
/ 2 = final temperature of water; 
w x = initial weight of water; 
w^ = final weight of water; 
p x = pressure of steam; 
r, and q x correspond to/ x ; 
<7, correspond to / a ; 
q 2 correspond to t % . 

Then 

O^ + ft - ft)(ze/ a - w x ) = wlq, - ft), 



54 ENGINEERING LABORATORY PRACTICE, 

from which 

Wifo - ?.) (9i ~ ft) 



*i = 



(<x> 2 — ze/^ 



This formula assumes that the constant of the in- 
strument is zero and that there is no radiation. The 
preliminary heating of the barrel, as explained above, 
makes the calibration-constant a negligible quantity, 
and if the test is of short duration it is customary to 
disregard the radiation. 

66. Calorimeter Exercise. — The apparatus con- 
sists of three calorimeters of different types connected 
to the same steam-supply and with the same manner 
of attachment. A suitable water-jacket is provided 
to govern the quality of the steam supplied. The 
different instruments used are: 

1. A throttling calorimeter. 

2. A separating calorimeter. 

3. A barrel calorimeter. 

Three observers are needed, one for each calorim- 
eter. Run simultaneous tests, adapting the time of 
observations on Nos. 1 and 2 to that which will be 
convenient for the barrel calorimeter. Run three 
tests, changing the quality of steam each time by 
means of the water-jacket on the steam-pipe. Let 
the observers change positions so that each will run a 
test on each calorimeter. 

In the Report present a copy of all running logs, 
table of calculated results arranged for convenient 
comparison, and a curve of the quality of steam shown 
by each calorimeter based upon a straight line repre- 
senting dry steam. For formula and directions con- 
cerning each calorimeter, see Sections 59 to 65. 



CHAPTER VIII. 
MEASUREMENT OF POWER. 

67. Classification. — Machines for the measurement 
of power may be divided into two general classes: 
those which absorb the power measured, called 
absorption-dynamometers; and those which form a 
connecting link in the transmission of the power to be 
measured, called transmission-dynamometers. 

68. Absorption - dynamometers. The Prony 
Brake. — The form of absorption-dynamometer in 
most common use is the Prony brake, of which there 
are many varieties. One of the simplest forms, which 
may be taken for illustration, consists of a rope placed 
over or wrapped around a pulley which receives the 
power to be measured. The rope is provided with 
adjustable weights, and the friction induced by the 
revolution of the pulley is such as to sustain the 
weighted end of the rope against gravity. An increase 
of load is obtained by adding more weights, which 
causes the rope to bear on the pulley with greater 
force, thus increasing the friction. Since it is difficult 
to obtain the weight which will just be thus sustained, 
it is customary to attach a spring-balance to the other 
end of the rope as a compensating device, as in Fig. 
15. The lower end of the balance is attached to 
some fixed point. 

55 



56 



ENGINEERING LABORATORY PRACTICE. 



The power absorbed by such a brake is given by 
the following formula: 

2 7tm( W — w) 

H.r . = , 

33OOO 

where r is the radius of the wheel plus half the 
diameter of the rope in feet, n is the revolutions per 




Fig. 15.— Rope Prony Brake. 

minute, W is the weight on the tight side of the rope 
and w is the weight on the slack side as shown on the 
spring-balance. 

A common modification of the rope-brake is the 
substitution of a steel band or bands for the rope. 
This band has attached to it at intervals of a few 
inches blocks of hard wood which bear on the wheel 
and form the rubbing medium. Another form of 
Prony brake is shown in Fig. 16. The parts lettered 
a and b are of hard wood, and the load is obtained by 
tightening the hand-wheel k. The load is measured 
by a platform-scale which registers the retarding 



MEASUREMENT OF POWER. 



57 



force at the radius r. Since the scale sustains not 
only the downward pressure due to the revolution of 
the pulley, but also the weight of the brake-arm itself, 
this latter amount must be ascertained and deducted 
from the reading of the scale to determine the power 




Fig. 16. — Block Prony Brake. 



given off by the pulley. By making W equal to the 
reading of the scale and w the weight of the brake-arm 
at the radius r, the above formula will apply to this 
form of brake. By slight modifications the same 
formula may be made to apply to all forms of the 
Prony brake. 

69. Special Forms of Prony Brakes. — In the 
Purdue Laboratory are several special forms of brakes, 
two of which will be here described. 

Pipe-brake. — This is a form of Prony brake in 
which four f-inch iron pipes are substituted for the 
rope. These pipes run in grooves turned in a wooden 
band bolted to the fly-wheel. A system of reducing- 
levers is introduced on the tight side to weigh the load, 
and a large spring-balance is employed to measure the 
back pull. This spring-balance is connected to an 
equalizing device by which the pull on all the pipes is 
maintained alike and the balance registers the pull on 



58 ENGINEERING LABORATORY PRACTICE. 

a single pipe. Water is circulated through the pipes 
to carry off the heat generated. 

In operating the brake, determine the load under 
which it is desired to run the engine and place enough 
weights on the scale-pan to equal this load. After the 
engine is started, tighten the hand-wheel on the slack 
side until the lever rises and floats at its middle posi- 
tion. 

The formula for horse-power is 

(3# — 4b -f- c)2 7trn 



H.P, 



33000 



where a is the weight on scale-pan not including 
weight of pan, b is the back pull as shown by the cor- 
rected spring-balance reading, r is the effective brake- 
arm, n is the revolutions per minute, and c is the 
unbalanced weight of scale-pan, lever, links, pipe, etc. 

The value of the constant quantities may be found 
in the Commonplace-book. 

Band-brake. — In this brake the power is absorbed 
by a steel band running on a heavy wooden pulley. 
The band is surrounded by a strip of muslin which 
receives and distributes a spray of water for cooling 
purposes. The wooden lever to which the ends of 
the band are attached rests upon platform-scales, and 
the load is applied by means of a hand-wheel which 
tightens the band on the pulley. The directions for 
management of the pipe-brake apply in a general way 
to this brake. The formula in Section 68 may be used 
by making the item w equal the unbalanced weight of 
the lever-arm and connections. The value of the 
brake-constants may be found in the Commonplace- 
book. 



MEASUREMENT OF POWER. 



59 



70. Transmission-dynamometers. — A form of 
transmission-dynamometer which may be easily and 
cheaply constructed has been devised by Prof. W. F. 
M. Goss. It is shown diagrammatieally in Fig. 17. 

This dynamometer consists of a differential lever by 
which the difference in tension of the two sides of a 
belt is determined. This lever is pivoted to a fixed 




a 





00 



s \d 

Fig. 17. — Belt Transmission-dynamometer. 

point and carries the pulleys b and c. It is pro- 
vided with a scale-pan s, and a combined dash-pot 
and counterweight d. The power transmitted by the 
belt is measured by the speed in feet per minute at 
which it runs multiplied by the difference in tension 
of the two sides, as shown on the dynamometer. The 
force tending to raise the left end of the lever is twice 



6o ENGINEERING LABORATORY PRACTICE. 

the tension t x of the tight side of the belt; that tend- 
ing to raise the right side is twice the tension / a in the 
slack side. Hence the resultant movement tending 
to produce rotation of the lever is twice the difference 
in tension of the two sides of the belt, acting on an 
arm bo (= oc) equal to the distance from the fulcrum of 
the lever to the center of the pulley supported by it. 
Since the lever-arm of the scale-pan ao is twice the 
above, a weight on the pan equal to the difference in 
tension of the belt will balance the lever. 

The belt speed is known from the revolutions per 
minute of the driven pulley and its circumference in 
feet. The formula for horse-power is 

ndnw 
H.P. = , 

33000 

where d is the diameter of the driven pulley plus the 
thickness of the belt in feet, n is its revolutions per 
minute, and w is the weight in pounds necessary to 
balance the lever. 

The observer in charge should keep such a weight 
on the scale-pan as will cause the lever-arm to move 
evenly between the stops. 

71. Efficiency of Screws. — The screw is one of the 
elementary mechanical forces and one that forms an 
essential part of a great variety of mechanisms. The 
efficiency of the screw may be defined as the ratio of 
the work done upon the screw to lift a given load 
through a certain height, to the work done by the 
screw in lifting. This ratio varies for different loads 
lifted. The factors in the first member of the ratio 
are the distance passed through by the moving force, 
expressed in any convenient unit, and the mean force 
exerted in pounds. The factors in the second member 



MEASUREMENT OF POWER. 6l 

of the ratio are the load lifted in pounds and the 
height through which it is raised. 

In order to determine the efficiency of the screw 
the following test may be made : The apparatus con- 
sists of a jack-screw fitted w T ith a lever of convenient 
length, say 36 inches, and a spring-balance at the end 
of the lever. The jack-screw is placed on the table of 
a testing-machine, which serves to register the load. 

Specific Directions. — Place the jack-screw to be 
tested on the center of the testing-machine table, 
with a block of hard wood above and below it. Balance 
the poise-lever and run the movable head down until 
in contact with the screw. Place the poise at the one- 
thousand-pound mark and run the head down until the 
poise-lever rises and remains in balance. Back the 
screw down and then run it up by means of the lever 
and spring-balance, and note the reading on the 
balance the instant the poise-lever rises. Be careful 
to exert the pull at right angles to a vertical plane 
through the lever-arm. Now move the poise to the 
two-thousand-pound mark, run the movable head 
down until this load is balanced, and repeat the test. 
Make six tests at one-thousand-pound steps, and 
repeat the observations once or twice under each 
load. At each test note the number of full threads 
exposed to view. 

In calculating the efficiency of the screw the de- 
termination may be based upon one complete revolu- 
tion of the screw. Although only momentary condi- 
tions are observed, these conditions may be assumed 
to hold true for a complete revolution. Suppose the 
height through which the screw is raised be equal to 
the pitch (p) of the screw in inches, or one revolution. 



62 



ENGINEERING LABORATORY PRACTICE. 



Let the load lifted be W pounds and the correspond- 
ing pull on the balance be P. Then the work done 
by the operator at the end of the lever-arm in raising 
the load, expressed in inch-pounds, will be 

2n X 36 X P. 

The work given out by the jack in moving the load 
will be 

p\V. 
The efficiency in per cent is therefore 

pW 
100 £ — ^ ^. 

27T X 36 X^ 

The Report should be made out on the form shown 
below. 

72. Form for 

EFFICIENCY TEST OF SCREW. 



Made by 



Date, 



Outside diameter of thread in inches 

Pitch " " " " 

Form of thread. . . . 

Effective length of hand-bar used in inches 



Load under which efficiency 
was obtained 

Work which the screw would 
do in one revolution, in inch- 
pounds 

Pull on lever in pounds 

Work which would be done 
upon the screw in one revo- 
lution, in inch-pounds.... 

Efficiency 



1 2.3 4 



Notes; 



MEASUREMENT OF POWER. 



63 



73. Efficiency of Hoists. — This test is conducted 
for the purpose of determining the relation between 
the work put into a chain-hoist on the hand-chain, and 
that given out by the hoist in lifting the load. The 
method consists in putting a definite load on the hoist 
and noting the stress or weight on the hand-chain 
necessary to keep the load moving upward; that is, 
the weight on the hand-chain necessary to keep the 
load moving after it has been started by hand, since 
the friction at starting is much greater than that after 
the load is in motion. 

Specific Directions. — In calculating the efficiency, 
the following factors are necessary: the value of the 
load raised, the weight on the hand-chain required to 
raise it, and the ratio of the velocity of the hand-chain 
to that of the load-chain. With the Weston differ- 
ential hoist, this velocity-ratio is equal to 2AL -f- 
(AL - AK\ Fig. 18. 




Fig. 18. 



But since the circumference is proportional to the 
radius, we may employ the number of link-pockets for 
our unit of measure: the velocity-ratio may therefore 
be found by subtracting the number of pockets in the 
small wheel from the number in the large wheel and 
dividing this difference into twice the number in the 
large wheel. With other forms of hoists, the ratio 



64 ENGINEERING LABORATORY PRACTICE. 

may be determined by experiment. Tie a piece of 
string on a link of the load chain opposite some fixed 
part of the hoist and put a similar piece on the hand- 
chain. Move the former a considerable distance and 
observe the corresponding movement of the hand- 
chain. Repeat several times and calculate the velo- 
city-ratio from the mean of the observations. This 
ratio should be expressed in the form of a fraction, 
the denominator being I. 

The weight lifted, in pounds, may be taken as a 
unit representing the work done; the stress in pounds 
on the hand-chain, multiplied by the fraction repre- 
senting the velocity-ratio, will measure the correspond- 
ing work put into the hoist. The efficiency in per 
cent is equal to 100 times the work delivered by the 
hoist divided by the work supplied. 

Make determinations in both hoisting and lowering 
with six loads, increasing by one-hundred-pound steps, 
and report on the form shown below. 

The last item on the report, " Ratio of work done 
by falling load to work done on hand-chain in lower- 
ing, " is not expressed as an efficiency, since the chief 
purpose of the hoist is to raise and not to lower the 
load. It should be expressed as a ratio thus: \ \ x\ 
the work done on the hand-chain being taken as the I. 

Note. — The weight of the scale-pans should be in- 
cluded as a part of the load. 



MEASUREMENT OF POWER. 



65 



74. Form for 

TEST OF HOIST. 



Made by 



Date, 



VELOCITY-RATIO 



Load lifted in pounds 

Stress on hand-chain in pounds. 

Work put into the machine 

Efficiency in hoisting 

Stress on hand-chain necessary 
to lower 

Work done in lowering 

Ratio of work done by falling 
load to work done on hand- 
chain in lowering 



123456 



Notes: 

75. Belt Testing. — Belts are tested to determine 
the power which they will transmit under different 
conditions of tension, speed, and load, and the coeffi- 
cient of friction between them and the pulley. 

The apparatus should be so arranged that the belt 
may be run under different initial tensions and the 
power absorbed by some form of brake. 

Specific Directions. — Run four tests of twenty 
minutes each, with initial tensions of 20, 40, 60, and 
80 pounds per inch width of belt. Let the brake load 
be as large as can be carried with a slip of not to 
exceed 3 per cent. 

Observe: 

1. Time. 

2. Revolutions of driving-pulley. 

3. Revolutions of driven pulley. 

4. Initial tension (when at rest). 

5. Total tension (in motion). 



66 ENGINEERING LABORATORY PRACTICE. 

6. Net load on brake. 

The Report should include, in addition to a copy 
of the Running Log, the following items: 

a. Kind of belt. 

b. Width and thickness. 

c. Condition of belt. 

d. Rough or smooth side to pulley. 

e. Diameter of driving-pulley, inches. 
/. Diameter of driven pulley, inches. 
g. Length of brake-arm, inches. 

h. Initial tension, per inch of width. 

t. Speed of belt, in feet per second. 
j. Slip, in per cent. 

k. Tension on tight side, T x . 

I. Tension on slack side, T^. 

m. Horse-power of belt. 

n. Equivalent horse-power at ioo feet per second. 

The per cent of slip is found as follows: 

Let r be the actual revolutions of the driven pulley, 
and r, the calculated revolutions without allowing for 
slip. Then the per cent of slip will be 

r, — r 
ioo— . 

The values of T x and 7^ are found as follows: The 
total tension on the belt is composed of the sum of the 
tensions on the two sides or item 5 = 7^ -f- 7!,. If 
T x and 7", are equal, no motion of the belt will result. 
If 7", be greater than 7!,, then motion will result and 
power will be transmitted proportional to that differ- 
ence. This is expressed by the following formula: 

T T J item <gQ X (item 6) 
J > y *- 2 - (item/) 



MEASUREMENT OF POWER. 67 

from which, with the relationship expressed above, 
the values of T i and T 2 can be found. 

76. Belt Slippage. — A knowledge of the slippage 
of belts is of importance when selecting sizes for 
pulleys, since it is evident that if this slip is neglected 
the driven pulley will fail to reach the intended speed. 

Specific -Directions. — The apparatus required to de- 
termine the per cent of slip consists of two speed- 
counters and a gong or whistle for signals. An ob- 
server with a counter in hand should be stationed 
at each shaft connected by the belt, while a third 
keeps time and log. Upon signal, the counters are 
applied simultaneously to each of the shafts and the 
revolutions taken for a given interval of time (two 
minutes), which is ended by a second signal. From 
the known diameters of the two pulleys calculate the 
number of revolutions which the driven would make 
in the interval covered by the observation, provided 
there were no slip, and let this be called r t . Let 
the observed revolutions of the driven pulley be r 2 . 
Then r, — r 2 will represent the slip, and the per cent 
of slip will be 

r, — r„ 

100 -. 

Several observations should be made and the results 
averaged. The Report should include width, thick- 
ness, and kind of belt, diameter of driver and driven 
pulleys; also the following: (a) revolutions of driver 
and driven per minute for each observation, and mean; 
{b) speed of belt in feet per second ; (c) revolutions 
which driven should make if no slip, average ; (d) slip 
in revolutions per minute, average; {e) per cent of 
slip, average. 

In connection with the report, solve the following: 



68 ENGINEERING LABORATORY PRACTICE. 

Problem. — A main shaft running at the rate of 200 
R.P.M. carries a driving-pulley 48 inches in diameter. 
What should be the diameter of the driven pulley in 
order that it may run at 300 R.P.M., there being no 
slip ? What should be its diameter if there is to be 
3 per cent of slip ? 

77. Tests of Paper Friction Wheels.— The use 
of paper wheels for the transmission of power is being 
rapidly extended, and a knowledge of their capac- 
ity and wearing qualities is correspondingly valu- 
able.* For the investigation of this subject a machine 
is in use in the Purdue Laboratory which consists of a 
paper pulley, driving a secondary shaft which is fitted 
with a Prony brake. The paper pulley is held against 
its follower by means of a bell-crank lever and weights. 
The experiments may be conducted according to the 
following : 

Specific Directions. — {a) Note lengths of lever-arm, 
diameters of pulleys, etc., unbalanced weight of 
levers, brake, etc. 

(b) Place on the scale-pan sufficient weights to make 
a normal pressure between pulleys of 75 pounds per 
inch of width. Place a light load on the brake and 
take simultaneous speed-readings of both pulleys, 
noting slip from known diameters of the two pulleys. 
Increase the brake-load to make about 5 per cent of 
slip, and repeat. Make tests with two intermediate 
brake-loads. 

(c) Change the normal pressure to 120 pounds and 
again to 140 and 160 pounds per inch of width, and 
repeat as under (b). 

(d) Report should cover all measurements and 
constants, tabulated logs of each test, giving time, 

* See paper on " Paper Friction Wheels," Trans. A. S. M. E., 
vol. xviii. p. 102. 



MEASUREMENT" OF POWER. 69 

speeds, brake-load, and normal pressure; a tabulated 
statement of results of each test giving normal pres- 
sure, horse-power transmitted, slip and coefficient of 
friction; and four curves showing relation of horse- 
power transmitted to normal pressure with constant 
slip, relation of horse-power to slip with constant 
pressure, and relation of coefficient of friction to slip 
with normal pressure constant, and to normal pressure 
with slip constant. 

The coefficient of friction in this case is the ratio 
of the tangential pull to the total normal pressure, and 
is calculated as follows: Let r be the effective brake- 
arm, r, be the radius of the driven pulley, p the net 
brake-pull, P the normal pressure per inch of width, 
and w the width of the narrower pulley in inches. 
Then the coefficient of friction is 



/= 



pr 
r x pr 



Pw ~ Pr.W 



Caution. — Wipe off surfaces of driver and follower 
with piece of perfectly clean waste, and see that bear- 
ings are oiled before starting. 



CHAPTER IX. 

STRENGTH OF MATERIALS. 

78. Testing-machines. — Machines for the testing 
of materials may be said, in general, to consist of 
(1) a power system by which stress is applied to the 
specimen, and (2) a weighing system by which the 
stress applied is measured. The power system may 
consist of a train of gears or an hydraulic cylinder, 
either of which may be operated by power or by 
"land. The weighing system usually consists of 
a system of levers and a poise by which the stress 
is balanced as on an ordinary pair of scales. An 
exception to this is the Emery Testing-machine, in 
which an hydraulic head and scale take the place of 
the system of levers commonly employed. In some 
Continental machines a mercury column is used to 
measure the stress. 

The usual form of testing-machine is that in which 
the load is applied through a train of gears and screws 
operated by power, and the stress is measured by a 
system of levers. They are of the vertical type, in 
which the tensional and compressional specimens are 
held in a vertical position. The vertical screws con- 
nected with the power system operate a movable head, 
to which the lower end of the tension specimen is 

70 



STRENGTH OF MATERIALS. 71 

connected. The upper end of the specimen is con- 
nected to the upper head which is a part of the 
weighing system and rigidly connected with the table 
of the machine, the latter resting in turn on the lever 
system. In compressional tests the specimen is placed 
directly between the movable head and the table. 

79. Riehle Screw-power Testing-machines. — 
In Fig. 19 is shown a Riehle Testing-machine of 
300,000 lbs. capacity. As shown in the cut, it is 
arranged for either tensional, compressional, or trans- 
verse tests. The screws s, s are operated by power 
through a system of gears shown under the frame of 
the machine. The speed of the screws is controlled 
and their motion reversed at will, by manipu'ation of 
the three levers, l lf / 2 , / 3 , located in a position near the 
poise-lever, convenient to the operator. These screws 
operate the movable head b. The upper head a is 
connected with the table t which rests on the system of 
levers e, f. g, h. Along the last lever, k, the poise p 
is made to travel by the hand-wheel w. The lever h 
is balanced by the adjustable counterpoise c. The 
head a may be raised or lowered to accommodate 
different lengths of specimens. 

For adjusting the machine four different speeds are 
provided, for both upward and downward movement. 
These are secured by manipulation of levers /„ / 2 , 
and / 3 . For testing, two speeds are provided, using 
levers l l9 / 2 , and handle i. 

Specimens may be tested in tension up to 6 feet in 
length, with an allowance for a total elongation of 
3 feet. 

In Fig. 20 is shown in perspective the Riehle 
patent high-faced wedge for flat specimens. The 



72 



ENGINEERING LABORATORY PRACTICE. 



serrated surface is slightly convex, and grips the speci- 
men first on a line parallel to its axis. As the wedge- 




Fig. 19. — Riehle 300,000-pouND Testing-machine. 

teeth sink into the specimen a hold is received over 
its entire width. It is claimed that by the use of this 
device a more centrally applied stress is secured. 



STRENGTH OF MATERIALS. 



73 



Fig. 21 shows a plan of the arrangement with the 
specimen D in place. The curvature of the faces of 
the wedges cc is exaggerated to render the action 





Fig. 20. — Riehle Patent 
High-faced Wedge. 



Fig. 21. — Arrangement 
of Wedges. 



more easily understood. For round specimens, 
wedges are provided with V grooves of different sizes, 
into which the specimen fits. 

80. Riehle 100,000-lb. Testing-machine. — In Fig. 
22 is shown a form of Riehle machine having a 
capacity of 100,000 lbs. The general arrangement is 
that usually employed. It differs from the previous 
example principally in the use of a fixed upper head. 
The machine shown in the cut is provided with a 
special form of automatic poise which adjusts itself to 
balance the increasing loads. The poise-lever is in 
the form of a screw, and the poise is a nut which is 
revolved on the screw by means of a train of gears and 
a splined rod back of the poise-lever and parallel with 
it. This is well shown by the detail view. The 
splined rod is driven by a belt operated from the 
driving-mechanism of the machine, and its motion is 



74 



ENGINEERING LABORATORY PRACTICE. 



controlled by an electromagnetic clutch carried on 
the back end of the poise-lever. The poise-lever is 
connected at its outer end to an auxiliary lever which 
carries at its free end two contact-points which 
operate the electromagnetic clutch. The operation 
is as follows: As a load is applied to the specimen, 
the poise-lever rises and the auxiliary lever falls, 




^O^ N\©V» o\ ^0\8», 



Fig. 22. — Riehle ioo,ooo-pound Testing machine. 

making contact with the lower contact-point. This 
energizes one side of the clutch, which, through the 
rod and gears, moves the poise-weight along the 
poise-lever until the latter is balanced and, falling, 
breaks the electric contact. If for any reason the 
load should decrease, contact would be made at the 
upper contact-point, the other side of the clutch 
would be energized, and the poise would be moved 
backward until a balance was secured. In later 



STRENGTH OF MATERIALS. 



75 



designs provision is made for adjusting the speed of 
travel of the poise to the size of the test-piece. 

81. Olsen ioo,ooo-lb. Testing-machine. — A de- 
sign of testing-machine of 100,000 lbs. capacity, made 
by Tinius Olsen & Co., is shown in Fig. 23. The 




Fig. 23. — Olsen ioo,ooo-pound Testing-machine. 

machine differs from those already described in the 
arrangement of the driving mechanism and the weigh- 
ing levers. Four straining-screws are employed, in- 
stead of two as in the Riehle machine. The poise- 
lever is fitted with a vernier-dial at its back end, 
which is graduated to 10 pounds. Several adjusting 



76 



ENGINEERING LABORATORY PRACTICE. 



speeds are obtained by manipulation of the two levers 
shown, and the slowest testing-speed is controlled by 
the hand-wheel, which throws a pair of grooved fric- 
tion-wheels into action. 




Fig. 24. — Riehle Hydraulic Testing-machine. 

82. Riehle Hydraulic Testing-machine. — Testing- 
machines are made by Riehle Brothers in which the 



STRENGTH OF MATERIALS. 77 

power is applied by hydraulic pressure. The train of 
gears, which forms the power-system in the usual 
design of machine, is replaced by an hydraulic cylinder 
connected to the movable head. Fig. 24 shows a 
Riehle hydraulic machine of 50,000 lbs. capacity. 
This type of machine may be conveniently used for 
stresses not exceeding the above-mentioned capacity. 
For stresses above that amount the leakage of the 
hydraulic cylinder renders the action of the machine 
unsatisfactory. 

As shown by the cut, the pump is situated on the 
table of the machine between the upright columns and 
the poise-system. The pump is operated by a handle 
which may be detached when not in use. Attached 
to the pump is a small check-valve controlled by a 
lever, which when opened allows the oil to fiow from 
the hydraulic cylinder back to the pump. This allows 
the large counterweight to raise the plunger with the 
attached movable head to its normal position after 
the breaking of a specimen. 

83. Emery Testing-machine. — One of the most 
accurate forms of testing-machines made is the Emery 
Hydraulic Testing-machine, made by Wm. Sellers & 
Company. The following description is given by the 
makers : 

The essential peculiarity of the Emery testing- 
machine is the method by which the stress produced 
upon the piece tested is conveyed to the scale and 
accurately weighed by mechanism that is entirely fric- 
tionless, and hence responds to the same increment 
of load regardless of the amount of strain upon the 
specimen. This result is accomplished by receiving 
the load upon a fiat closed cylinder called the 



78 ENGINEERING LABORATORY PRACTICE. 

" hydraulic support." The general scheme is indi- 
cated in Fig. 25, which shows merely the relation of 
the parts, no attention being paid to proportion. 

The depth of the hydraulic-support cylinder A is 
exceedingly small. The end is closed to prevent the 
escape of the contained fluid by a thin sheet of metal, 
b y upon which rests a piston, c, considerably smaller 
than the internal diameter of the cylinder; this piston 
is secured to the cylinder by thin flexible fixing-plates, 
dd, which permit a very small movement in the direc- 
tion of the axis of the cylinder while rigidly securing 
it against any lateral movement. This longitudinal 
movement of the piston from no load to full load is 
not more than .003 inch, and as there is no hydraulic 
packing and no sliding, there is no friction beyond 
that of the fluid. This hydraulic chamber is connected 
by a pipe e, with a smaller but similar chamber B, 
placed in the scale; the piston c f of this latter cham- 
ber acts through the block H against the first lever C 
of the scale, which thus receives a fraction of the load 
upon the piston c determined by the relation between 
the areas of the two hydraulic cylinders A and B. 

The scale-body is a rigid cast-iron frame carrying 
the steel scale-levers, all the supports and connections 
of which are thin, flexible plates of steel firmly secured 
to the levers and their supports, and having a sufficient 
exposure between their fixed ends that the amount 
of bending due to the movement of the levers shall be 
well within the elastic limit of the material. The long 
arm of the lever C is coupled by the bar D with the 
short arm of the poise-frame lever E\ the long arm of 
this lever carries all the standard weights of the scale, 
and the method of putting them on or taking them 



STRENGTH OF MATERIALS. 



79 




80 ENGINEERING LABORATORY PRACTICE. 

off, without handling, is peculiar to the Emery sys- 
tem. Suspended from this lever E at suitable inter- 
vals by thin fulcrum-plates are " poise-frames " N> 
consisting of an upper cross-head >S and a lower cross- 
head T, united by three vertical bars disposed at equal 
intervals about the cross-heads. 

These bars are provided on their faces with short 
projecting brackets V, having a horizontal surface and 
a bevelled surface corresponding with similar surfaces 
formed on the weights k, which are short cylinders or 
rings with bevelled edges; the weights are carried by 
the flat surfaces and centered by the bevelled surfaces. 
A " weight-frame/* M, for carrying the weights when 
not in use, of similar construction, has its three verti- 
cal bracketed bars alternating with the bars of the 
poise-frame; this weight-frame is guided, and is raised 
and lowered in a vertical line without touching the 
poise-frame, by a rock-shaft and a hand-lever coupled 
to the rod projecting from the cross-head R. The 
brackets on the weight-frame bars are differently 
spaced from those on the poise-frame, and when the 
weight- frame is at the top of its stroke it carries all 
of the weights clear of the poise-frame; a small move- 
ment downwards transfers one weight to the poise- 
frame, the bevelled surfaces on the brackets centering 
the weight if it becomes displaced sideways by a too 
sudden movement. A further movement transfers 
another, and so on ; that is, the movement of the 
weight-frame in either direction transfers the weights 
singly and successively from one frame to the other; 
the weights f and g are shown carried by the poise- 
frame, j and k by the weight-frame, while h is being 
transferred from one to the other. 



STRENGTH OF MATERIALS. 8 1 

The operating hand-lever is provided with a notched 
segment, into which a click-spring plays so that the 
operator feels when he has moved the lever the right 
distance to transfer a weight to or from the poise- 
frame without having to watch the indicator as 
formerly, and the arrangement of the six bars sur- 
rounds the weights by a cage that effectually prevents 
any displacement and consequent interruption of the 
test, as sometimes occurred when the weights rested 
on simple shelves secured only by short-pointed pins. 
There is hence no necessity for opening the glass case 
that encloses this part of the scale, and the weights 
are never exposed to any risk of alteration. The 
weights in the first poise-frame have a value of ioo 
pounds, the next frame carries weights of a value of 
ten times as much, or iooo pounds, the next 10,000 
pounds, and so on; and the readings are summed up 
by a series of segments connected to the several 
operating shafts and provided with figures denoting 
the number of weights on each poise-frame. A hori- 
zontal slot in a vertical plate near the upper left-hand 
corner of the scale is so placed that the reading of the 
figures shown through this slot denotes the number of 
pounds pressure applied to the specimen. 

The final lever of the scale is an indicator-needle/ 7 , 
which has a movement at its point of if to 2 inches, 
and this movement, calculated from the mechanical 
ratios of the hydraulic chambers and of the levers in 
the scale, is not less than 300,000 times the movement 
of the piston c in the first hydraulic chamber, and may 
on large machines be 6,000,000 times as much. The 
transfer of fluid from one chamber to the other is 
almost imperceptible, and while it takes force to move 



82 



ENGINEERING LABORATORY PRACTICE. 



the metal sheets and to bend the steel fulcrums, yet 
this force is all returned as the various parts resume 
their position of equilibrium, the needle returning to 




3 

u 

< 

i 
o 

H 
w 

W 

H 
>< 

W 

W 

o 

Q 
<J 
w 

W 

■ 

I— I 

w 
o 

w 



fe o 

3 3 



o 

b 

CO 



the same zero-point after being disturbed in either 
direction. 

The weighing-head. Fig. 26, consists of two circular 
or annular beams, 65 and 69, firmly secured together 
by bolts placed around their periphery, and by the 



STRENGTH OF MATERIALS. 83 

straining-screws which pass through both beams and 
clamp them by a shoulder and nut. This head and 
the straining-head fit easily upon the bed which main- 
tains the axes of the two heads in the same straight 
line. A draw-bar, 70, is secured in the axis of these 
beams by two thin annular steel plates, 72 ; these 
plates hold the draw-bar securely in line with the axis 
of the machine, while permitting a free motion to a 
limited extent in the direction of the axis. The pro- 
jecting end of the draw-bar is provided with a screw- 
thread by which the compression-platform or the ten- 
sion-holder is secured to it. The draw-bar is enlarged 
in the middle, and against each of the two shoulders 
thus formed is secured a thin annular steel plate, 73; 
these plates are for the purpose of carrying and center- 
ing the hydraulic support, which is made annular, 
instead of circular, as shown in Fig. 25. The hy- 
draulic support is maintained in fixed relation with 
the draw-bar laterally, while it is left free to move 
relatively to it in the direction of its axis through the 
small distance required. On each side of the hy- 
draulic support steel collars, 71, are screwed and 
secured to the draw-bar; these collars are provided on 
the periphery with a series of ribs (Fig. 26, 4) parallel 
with the axis of the draw-bar, and which lie between 
without touching, similar ribs projecting from the 
interior surface of the annular beams. The ends of 
all these ribs on the two beams and the collars are 
accurately faced to true planes at right angles to the 
axis of the draw-bar, and the distance between the 
two extreme faces of the hydraulic support is made 
slightly less than the distance between those two 
planes. Movement of the draw-bar in either direction 



84 ENGINEERING LABORATORY PRACTICE. 

carries the hydraulic support against the ends of the 
ribs in one annular beam, brings the ends of the ribs 
on one of the collars on the bar against the opposite 
side of the hydraulic support, and produces pressure 
on the contained liquid which is transmitted through 
the pipe 63 to the small hydraulic chamber in the 
scale. 

In order to prevent the shock of recoil, resulting 
from the rupture of a large specimen of high steel, 
from doing injury to the thin brass plates in the 
hydraulic support, the abutting piece 64 of the sup- 
port which rests against the ribs in the annular beam 
65, when strains of tension are applied, is made larger 
in diameter than the hydraulic support proper, and is 
provided with a spiral or screw-face, 66, which engages 
with a corresponding screw-face formed on a rotable 
ring, 67, fitting in the other annular beam, 69. After 
the initial load has been applied this ring is rotated 
by the pinion-shaft 68 to bring the screw-faces in 
contact (see Fig. 26, 3), and the abutting piece 64 
is thus clamped firmly to the annular beam against 
which it rests. When the specimen breaks its first 
blow is delivered through the draw-bar and ribbed 
collar to this abutting piece, 64, which transmits it 
through the ring 67 to the rear annular beam, 69, 
and as these beams 65 and 69 are rigidly united, the 
blow is absorbed by the total mass of these two beams. 
The hydraulic support is thus thoroughly protected, 
and these machines can be used regularly for breaking 
high steel specimens up to the full capacity of the 
machine without any risk of injury. 

The weighing-head is returned to its place on the 
bed after movement due to recoil by a set of spiral 



STRENGTH OF MATERIALS. 8$ 

springs locked up in boxes secured to the bed; these 
springs are strong enough to move the head, and their 
resistance diminishes greatly the movement due to 
recoil, while the friction of the head upon the bed 
rapidly wipes out the oscillations. The annular 
beams, bolted together as described, constitute one 
built-up beam to resist the bending due to the pres- 
sure on the draw-bar midway between the straining- 
screws. The hydraulic support is thus inclosed in a 
rigid mass of cast iron and effectually protected 
against injury from violence or from being gummed 
up by oil from the straining-cylinder, as has occurred 
with the upright machines, and the frictionless move- 
ment of this support under all conditions of service is 
thus insured. 

The draw-bar is provided with suitable grips and 
holders for tension or compression specimens. 

The Emery testing-machines are now made hori- 
zontal instead of vertical: in the first place to make 
all sizes of machines of one type, and in the second 
place to get certain advantages in overcoming the 
shocks of recoil. The stress is produced by a 
" straining head/' which is an hydraulic cylinder with 
a piston packed to receive fluid pressure in either 
direction, and the piston-rod passing through a packed 
bearing in one end is provided with a screw-thread, 
similar to that on the draw-bar, to receive the various 
holJers. The fluid is supplied to this straining-cylin- 
der through two systems of jointed pipes, which are 
connected through the valves at the scale-case with 
the pressure-pump and the tank respectively, so that 
each pipe acts either as a pressure-pipe or an exhaust- 



86 



ENGINEERING LABORATORY PRACTICE. 




an 

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(JTj 



O 

< 

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Q 

> 

H 

O 

o 
u 

o 



W 
I 

M 

6 



STRENGTH OF MATERIALS. 87 

pipe, depending upon the direction in which the strain 
is to be exerted upon the specimen. 

The weighing- and straining-heads are mounted on 
a suitable frame or bed and are held together by 
heavy straining-screws. 

In Fig. 27 is shown a special form of Emery 
machine of 30,000 pounds capacity for weighing the 
tractive force of locomotives on shop testing-plants. 
The draw-bar of the locomotive is connected to the 
draw-bar of the weighing-head, and the latter thus 
receives the stress due to the tractive force. The 
weighing-head is provided with mechanism for pro- 
ducing an initial stress upon the draw-bar in either 
direction. This initial tension for the machine illus- 
trated is equal to about 25,000 pounds, and operates 
to push the draw-bar ahead when the locomotive is 
running forward and the reverse when it is running 
backward. A special form of scale is used in which 
the levers are provided with sliding-weights, as in an 
ordinary pair of scales, instead of the arrangement 
shown in Fig. 25. Provision is made for raising or 
lowering the weighing-head to accommodate different 
heights of draw-bar. 

84. Riehle Wire-tester. — A very convenient form 
of wire-tester is shown in Fig. 28. The power is 
applied by a hand-wheel which gives motion to one 
pair of grips through the medium of a nut and splined 
collar. The other pair of grips is attached to an ac- 
curate spring-balance, reading to 600 pounds. The 
needle of the balance is so arranged that it remains 
at the highest point reached, after fracture takes 
place. Provision is made for taking up the recoil 
after fracture, to prevent injury to the balance. The 



88 



ENGINEERING LABORATORY PRACTICE. 



machine is arranged for quick adjustment to accom 
modate different lengths of specimens. 




X 

I 

CO 

6 



85. Olsen Cement-testing Machine. — A special 
form of machine for testing cement is shown in Fig. 
29. The specimen is held between two shackles and 



STRENGTH OF MATERIALS. 



8 9 



the power is applied slowly by means of a hand-wheel. 
A system of levers weighs the load to which the 
specimen is subjected, the poise being conveniently 
moved by means of a small hand-wheel and endless 
cord. 




Fig. 29. — Olsen Cement Testing-machine. 

86. Accessory Testing Appliances. Riehle-Yale 
Extensometer. — In order to determine the elastic 



90 



ENGINEERING LABORATORY PRACTICE. 



limit and modulus of elasticity, it is necessary to 
know the rate of deformation of the specimen as 




Fig. 30. — Riehle-Yale Extensometer. 

stress is applied. For this purpose, use is made of an 
instrument known as an Extensometer, one form of 



STRENGTH OF MATERIALS. 91 

which is shown in Fig. 30. This form is usually used 
in tensional tests, but may also be used to a limited 
extent in compressional tests. The instrument con- 
sists of a pair of clamps, each fitted with three sharp- 
pointed thumb-screws, by which they may be fastened 
to the specimen. A distance-piece or spacer is so 
arranged that the clamps will be exactly 8 inches 
apart. This distance-piece is removed as soon as the 
instrument is in place and before the stress is applied. 
The upper clamp carries two rods fitted at their lower 
ends with adjustable contact-points. The lower clamp 
is fitted with two micrometer-screws, reading to ten- 
thousandths of an inch, by which the elongation is 
measured. Electrical connection is made, as shown, 
with a battery and bell. The ringing of the bell 
announces the completion of the circuits at the points 
P and P r as the micrometer-screws are raised to 
measure the elongation of the specimen. By this 
means a uniform pressure of contact is secured. 

87. Autographic Recording Apparatus. The 
Henning Portable Recorder. — The Autographic Re- 
corder is an instrument for producing stress-strain 
diagrams or curves showing the variation of strain 
with stress. One of the newer forms of autographic 
recorders is the Henning Portable Recorder, shown in 
Fig* 3 1 - The drum is attached by means of cord and 
pulleys to the poise, and revolves in proportion to the 
increasing stress. A proper reduction of the length 
of travel of the poise is made. The stretch of the 
specimen actuates the pencil-lever, the movement of 
the latter being ten times the elongation of the speci- 
men up to elastic limit. After that point is reached 
the pencil-lever strikes a stop and is then raised bodily 



9 2 



ENGINEERING LABORATORY PRACTICE. 



with its carriage, giving a record directly proportional 
to the elongation. The instrument can be applied to 




Fig. 31. — Henning Portable Recorder. 



specimens from £ inch in diameter to 2 by if inches 
in cross-section. It can be used for compression as 
well as extension, and may be used for gage-lengths of 
6, 8, 10, and 12 inches. The wedges must be blocked 



STRENGTH OF MATERIALS. 



93 



up when the instrument is kept on the specimen to 
the point of rupture. 

88. Deflectometer. — This instrument, Fig. 32, may 
be used to record the contraction of short specimens 
under compressional stress or the deflection of speci- 




Fig. 32. — Deflectometer. 

mens under transverse stress. The cut shows the 
manner of arranging the instrument and renders 
further explanation unnecessary. 

89. Laying off Gage. — As is explained later, speci- 
mens in tension are sometimes marked for a length of 
8 inches in one-inch lengths, preparatory to testing. 
The instrument shown in Fig. 33 is conveniently 



iiiiiSiniVillP^liiillliPii! 



llilRlEHDE 



40 .30 2 ^Jjll'l'l 

■■||||l|ll , m'||"1'""lllllllllllll:!lllHllmi 



r\X\T\Tvr\j\j 



Fig. 33. — Riehle Laying-off Gage. 

arranged to assist in marking the specimen. At one 
end of the gage is a per-cent scale, arranged to read 
directly the per cent of elongation in 8 inches after 
fracture, 

90. Methods of Testing. Tension. — Materials 
are tested in tension to determine, among others, the 
following properties, viz.: Ultimate Strength, Elastic 
Limit, Moduli of Elasticity and Resilience, Percen- 



94 ENGINEERING LABORATORY PRACTICE. 

tage of Elongation, and Reduction of Cross-sectional 
Area. 

91. Definitions. — Ultimate Strength. — The ulti- 
mate strength may be defined as the maximum stress 
borne by the specimen per square inch of original 
area. 

Elastic Limit. — Considerable confusion exists in the 
definition of the elastic limit. The term is used to 
indicate three different points: 

(1) The unit-stress beyond which a portion of the 
deformation remains permanent after the load has 
been released. 

(2) The unit-stress at which the deformation ceases 
to be proportional to the load applied, i.e., the " pro- 
portional elastic limit." 

(3) The point in the stress-strain diagram where 
the deformation increases rapidly without any increase 
in the load, or the unit-stress corresponding to the 
scale-beam load when the beam, which has been kept 
balanced, " drops' ' suddenly. 

The detection of the first elastic limit involves a 
release of the load, and presents many practical 
difficulties. Indeed any load produces a slight set. 
The second elastic limit is the elastic limit ordinarily 
determined when an extensometer is used. With 
the ordinary material encountered it is not very de- 
finite, especially when very delicate measurements are 
made. The third or " apparent " elastic limit, that 
measured in commercial testing, and by best usage 
called the " yield-point, " is most easily fixed, and 
most valuable. In determining the yield-point, the 
student will do well to check the scale-beam indica- 
tion by using a pair of dividers as follows; 



STRENGTH OF MATERIALS. 95 

Space the dividers eight inches, and put one leg in 
the lower gage-mark. Chalk the surface of the speci- 
men around the upper gage-mark. As the test pro- 
gresses swing the upper end of the divider to mark a 
line on the chalked surface. The space between these 
lines will widen rapidly at the yield-point. Note also 
that just above the yield-point the specimen begins to 
scale. 

The following definition of apparent elastic limit 
has been proposed by Prof. J. B. Johnson:* The 
apparent elastic limit is the point on the stress- 
diagram of any material, in any kind of test, at which 
the rate of deformation is 50 per cent greater than it 
is at the origin. 

Modulus of Elasticity. — This is the number express- 
ing the ratio of the stress per square inch to the 
deformation per inch accompanying that stress, within 
the elastic limit. Thus if P equal any increase of 
stress per square inch, and d is the total increase of 
deformation under that load, per inch of length, ex- 
pressed in inches, then the modulus of elasticity 

E = P/d. 

We may, in determining this modulus, use for d 
the average deformation per inch corresponding to 
successive increments of load of impounds per square 
inch, these deformations being observed between cer- 
tain specific limits. 

Modulus of Resilience. — The modulus of resilience 
is the amount of work, in foot-pounds, done on a 
cubic inch of the specimen up to elastic limit. It is 

* " Materials of Construction," by J. B. Johnson. John Wiley 
& Sons. 



9 6 



ENGINEERING LABORATORY PRACTICE. 



equal to one half the load per square inch at elastic 
limit multiplied by the total elongation in feet, per 
inch of length up to elastic limit; or to the square 
of the load at elastic limit divided by twenty-four 
times the value of E. 

Percentage of Elongation. — This is the ratio of the 
total elongation of the specimen to its original length, 
measured between two gage-marks, usually placed 8 
inches apart. It is a measure of the ductility of the 
material. 

Reduction of Cross-sectional Area. — This is the ratio 
of the smallest area after fracture to the original area 
of the specimen. 

92. Form of Specimens for Tension. — Forms of 
specimen conforming closely to those recommended as 
standard by the French Commission are shown in Fig. 
34. They are arranged so that the per cent of elon- 



-i-d- 



V 



8d- 



^E*Sff 



■Ad? 



-4-6- 



> Wb 



9V~M- 



KVfT 



ih 



Fig. 34.* — Standard Forms of Specimens for Tension. 

gation shall be the same, for the same material, when 
different lengths of specimen are used. It will be seen 
that the recommended relation between gage-length 
and cross-sectional dimensions is, for round speci- 
mens, 

/= Sd, 



* Reproduced from Johnson's " Materials of Construction," 



STRENGTH OF MATERIALS. 97 

and for square specimens 

/ = 9 Vbi. 

For cast iron and for some other materials special 
forms of specimens are used in place of those men- 
tioned above. 

The specimens should be prepared with great care. 
The machining should be done in such a manner that 
the material is not torn or otherwise weakened, and it 
is recommended that all machined surfaces be finished 
by filing. When a sheared specimen is straightened, 
this straightening must be done cold. 

93. Method of Testing for Ultimate Strength. — 
This test is the one commonly employed in commer- 
cial testing to determine the characteristics of metals 
in tension. For purposes of comparison it serves as 
a fair indication of the quality of the material. 

Specific Directions. — The specimen should first be 
examined for cracks and flaws, as these may seriously 
affect the results of the test. Such defects should be 
noted on the report. The specimen should then be 
carefully measured in all dimensions, reading the 
dimensions of the cross-section to the thousandth 
of an inch, and making the record on the blank 
form. If the length of the specimen will permit, 
marks should be made upon it an inch apart for a 
space of eight inches. The outside marks are called 
gage-marks. This is done with a laying-off gage, and 
is for the purpose of determining the elongation after 
rupture. 

Balance the machine on which the test is to be 
made, first noting that the four check-nuts at the 
corners of the table are only loosely screwed down. 



98 ENGINEERING LABORATORY PRACTICE. 

After balancing the machine, the specimen should 
be carefully placed between the wedges, care being 
taken to have it centrally and vertically located. The 
wedges should be oiled on the back with heavy oil 
before being placed in position. 

Start the machine at a slow rate of speed and keep 
it running continuously until fracture occurs. Note 
the time of starting the test and the time when frac- 
ture occurs. The test should last from five to ten 
minutes. 

The scale-beam should be kept floating at all times 
during the test. When operating machines fitted with 
a hand-poise, take care not to run the poise out 
beyond the point necessary to float the beam, and do 
not run it back when the beam falls for any reason, 
unless the maximum stress has been reached and it is 
desired to find the load at the point of rupture. In 
such a case be sure to note the maximum load before 
moving the poise back. 

The following points should be noted: 

1. Time of starting test. 

2. Load on specimen when the beam first falls. 
This is called the yield-point, and occurs at from 50 to 
75 per cent of the maximum load. Do not confuse 
this with drop of the beam due to slipping of the 
wedges. 

3. Maximum load. 

4. Load at rupture. 

5. Time of rupture. 

After rupture occurs, stop the machine, remove the 
specimen, clean and return the wedges to their proper 
place. Leave the testing-machine in good order. 

Place the fractured ends of the specimen carefully 



STRENGTH OF MATERIALS. 99 

together, measure the elongation in eight inches, and 
determine the per cent of elongation. With a vernier 
caliper determine as closely as possible the minimum 
area of the fracture. 

In the case of the more ductile metals a rapid pull- 
ing out occurs near the point of fracture just before 
breaking. When this occurs the measured amount 
of elongation will vary in the same material, according 
as the fracture is between or near the gage-marks. If 
the fracture were just midway between the gage- 
marks, nearly all of the elongation would fall between 
those marks, and the measured elongation would be a 
maximum. But if the fracture should occur near a 
gage-mark, much of the elongation would fall outside 
of the marks, and the measured elongation would be 
less than in the previous case, To correct for this 
variation, an " equivalent elongation " may be calcu- 
lated by the following method: 

Suppose the specimen to be divided into x equal 
spaces between gage-marks, and that the fracture is y 
spaces from the nearest gage-mark. Mark two points, 
A and B (Fig. 35), on the long piece at y and \x 



I B 



DC 



Fig. 35. 

spaces, respectively, from the fracture. Place the 
pieces carefully together and measure from the gage- 
mark on the short piece to point A. This distance 
plus twice the measured distance fromyi to B should be 
taken as the final length of the specimen, and minus 
the original length, is called the equivalent elonga- 
tion. In some specifications it is required that the 



IOO ENGINEERING LABORATORY PRACTICE. 

fracture shall occur within the middle third of the 
length. 

The fracture should be carefully examined and pro- 
nounced either coarse or fine, and in metals either 
fibrous, granular, crystalline, or silky. It should also 
be noted as plane, oblique, cup-shaped, half-cup, or 
irregular. Tie the two pieces of the broken specimen 
together, attach a card on which is noted the kind of 
material, and the principal results of the test and place 
in the case provided for the purpose. 

The Report should be made out on the blank form 
for " Tensional Tests," and should include the fol- 
lowing items: Kind of material, sketch of specimen, 
dimensions of cross-section, area of cross-section, dis^ 
tance between gage-marks, time of test, yield-point, 
maximum stress, ultimate strength, reduction of area, 
percentage of elongation (actual), equivalent elonga- 
tion, sketch of fracture, character of fracture, notes. 

94, Determination of Elastic Limit by the Exten- 
someter. — In the determination of the elastic limit 
by the extensometer, the test is conducted in sub- 
stantially the same manner as that prescribed for find- 
ing the ultimate strength, except that instead of a 
continuous application of stress from start to the 
point of rupture the stress is applied in definite incre- 
ments, and after the application of each increment the 
test is stopped and a measurement made of the 
deformation. For this purpose an extensometer, a 
description of one form of which is given in Section 
86, is used. These measurements are continued until 
shortly after the elastic limit is reached, when the 
instrument is removed and the stress applied con- 
tinuously up to the point of rupture. 



STRENGTH OF MATERIALS. IOI 

Specific Directions. — Prepare the specimen and 
place in the testing-machine as directed in Section 93. 

From the known properties of the material under 
test, determine approximately the probable load per 
square inch at elastic limit, and reduce this to the 
corresponding actual load. Divide this actual load 
into twenty (20) equal increments and enter them in 
tabular form on the extensometer log. 

Place a load corresponding to one increment on the 
specimen and then place the extensometer in position. 
In adjusting, be sure that the clamps are concentric 
with the specimen and that the axes of the microm- 
eter-screws are parallel with and equidistant from it. 
In tightening the adjusting-screws be careful not to 
overstrain them. See that the contact surfaces are 
clean and the electric circuit in order. In attaching 
the wires to the extensometer, so arrange them that 
there will be no tension in them tending to pull the 
instrument out of line. 

Now take a zero-reading. This is done in the fol- 
lowing manner: Place the micrometer on one side at 
zero and move the upper contact piece until contact 
is made as shown by the ringing of the bell. Now 
back the upper screw off, and again bring it down until 
the bell just begins to ring. Then back the micrometer 
away from the upper contact point. Repeat the 
operation on the opposite side. 

Apply the second increment of stress to the speci- 
men and take a reading of the extensometer, this time 
having the upper contact pieces in their original posi- 
tion and making contact by means of the micrometer- 
screws. Repeat this process as rapidly as practicable 
until the sudden increase in the rate of deformation 



102 ENGINEERING LABORATORY PRACTICE. 

indicates that the elastic limit has been passed. 
Remove the extensometer, and finish the test as pro- 
vided in Section 93, under the head of Ultimate 
Strength. 

The Report should be made out on the blank form 
for tensional tests, and should be accompanied by the 
extensometer log and a stress-strain diagram (see 
Section 95). The items called for in addition to 
those given for tests of ultimate strength are: Elastic 
limit, modulus of elasticity, and modulus of resilience. 
Calculate the modulus of elasticity between the limits 
of 8000 and 18,000 lbs. stress per square inch. 

95. Stress-strain Diagrams. — The stress-strain 
diagram is a curve, the ordinates of which represent 
the stress on the specimen in pounds per square inch 
and the abscissae represent the corresponding total 
deformation per inch of length. From an inspection of 
this diagram the behavior of the material under stress, 
and in a general way its characteristics, may be deter- 
mined. For most materials the diagram will be nearly 
a straight line up to the elastic limit. In Fig. 36 is 
shown a typical diagram in two scales for wrought 
iron. 

In case the diagram is plotted from the results of 
an extensometer test, it can only be drawn to a point 
a little beyond the elastic limit. Such a scale should 
be chosen as will exhibit to best advantage the char- 
acteristics of the curve. Make the even thousands 
come at the heavy division-lines on the coordinate 
paper. See to it that the diagram can be read easily. 

To determine the modulus of elasticity, E y from the 
strain-diagram, proceed as follows: From the abscissa 
representing an elongation of .001 inch per inch of 



STRENGTH OF MATERIALS. 



103 



specimen, erect an ordinate to intersect the line drawn 
from the origin parallel to the straight part of the 
stress-strain curve. Find the stress corresponding to 





/ 


















f 




































































1 


z 


















hi 

Q. 


















Z 

O 

H 
< 


















O 

Z 
O 
_J 
Id 


























































HONI 


3uvn 


is 


s y3 


J SON 


nod 







Q 

6 3 



83 



s 



3§ 



z © 



10 © 
© rt 



pi 
h 

I 

en 

W 

H 



to 



the point of intersection. This multiplied by 1000 
will give E. 

To find the point on the diagram corresponding to 
the yield-point (Section 91) draw to the stress-strain 
curve a tangent which has an inclination 50 per cent 



104 ENGINEERING LABORATORY PRACTICE. 

greater than the straight line from the origin to the 
elastic limit. The point of tangency will be the 
yield-point. 

96. Autographic Records. — Many forms of instru- 
ments have been devised for autographically produc- 
ing a stress-strain diagram during the progress of the 
test. One of these, the Henning Portable Recorder, is 
described in Section 87. In the majority of designs 
two movements are provided: one a drum-movement, 
attached to the weighing-poise and revolving in pro- 
portion to the outward movement of the latter; and 
the second a pencil-movement, connected in some 
manner with the specimen and moving in proportion 
to the deformation of the latter. In the best designs 
two rates of pencil-movement are provided. Up to 
elastic limit the movement is magnified to render the 
characteristics of that part of the curve more easily 
seen. After elastic limit the rate of movement is 
much slower, in order that the latter part of the 
curve may be kept within reasonable limits. 

97. Methods of Testing in Compression. — Ma- 
terials are tested in compression to determine their 
crushing strength and strength to resist bending; also 
at times their elastic limits, and, if ductile, their 
plastic limits. Short specimens, those whose length 
is less than five diameters, usually fail by crushing or 
flowing. Long specimens usually fail by bending 
toward the side of least resistance. 

98. Short Specimens. — The materials may be 
divided into two general classes, in accordance with 
their behavior when subjected, in short specimens, to 
compressional stress. In the first classification are the 
plastic materials, such as wrought iron, soft steel, 



STRENGTH OF MATERIALS. 10$ 

copper, the alloys, etc., which fail by flowing. After 
the elastic limit is passed, further compression results 
in an increase of the cross-sectional area under a con- 
tinually increasing load. For such materials there are 
two fixed points independent of shape of specimen, 
i.e., the elastic limit and the plastic limit. It has 
been found that the elastic limit of these materials is 
nearly the same as their elastic limit in tension, and 
for this reason and in view of the difficulty of measur- 
ing the deformation of short specimens, compressional 
tests upon them are seldom made. 

The second classification embraces the brittle ma- 
terials, such as stone, brick, wood, cement, cast iron, 
etc., which fail by crushing due to the shearing on 
definite angles. With these materials the ultimate 
strength is easily determined. 

Preparing the Specimen. — If the material be metal, 
the specimen should preferably be turned and the ends 
faced up carefully to insure that they are plane and 
perpendicular to the axis of the specimen. If the ma- 
terial be of stone, cement, or some similar substance, 
the specimen is usually cubical in form; and the bear- 
ing-surfaces should be made as nearly plane and parallel 
as possible by grinding, and should then be bedded in 
a thin layer of plaster of paris. Sized paper should 
be put between the specimen and the plaster of paris 
bed to prevent absorption of water by the specimen. 
To secure a true bed, the plaster is allowed to set for 
about ten minutes while the specimen is on the table 
of the testing-machine, the movable head being run 
down in contact with the upper layer of the bed. 
The use of pasteboard or lead liners is not recom- 
mended. 



106 ENGINEERING LABORATORY PRACTICE. 

Specific Directions. — Prepare the specimen as di- 
rected above. Measure all dimensions and record on 
the blank report-sheet furnished. Balance the testing- 
machine with the specimen on the table. Apply the 
stress continuously until rupture occurs, or, in the case 
of the plastic materials, until the amount of deforma- 
tion is quite marked. In the case of stone, cement, 
etc., if the specimen begins to spall or flake off before 
rupture occurs, note the load when such action begins. 
Avoid injury from flying fragments. Take the time 
of starting and stopping the test. If the conditions 
of the test are proper, but little spalling will occur. 
The specimen will break suddenly, and the interior 
cone or pyramid will be evident. 

The Report should include the following items: 
Kind of material, sketch of specimen, dimensions of 
cross-section, area of cross-section, height, time of 
test, maximum stress, ultimate strength, sketch of 
specimen after test, notes. When a compressometer 
is used, a stress-strain diagram should be constructed. 

99. Long Specimens or Columns in Compression. 
— A specimen of length greater than ten diameters 
usually fails by bending toward its side of least resist- 
ance. The maximum strength of an ideal or perfect 
column, centrally loaded, must be taken as the load 
obtained by multiplying the area of cross-section by 
the elastic limit of the material, a result independent 
of the length. The unavoidable imperfections of 
material and of workmanship and the difficulty of 
centering the load will, however, produce some bend- 
ing before this maximum load is reached. 

When the column is once bent, the deflection 
increases rapidly, and the material on the concave side 



STRENGTH OF MATERIALS. 107 

of the column is subjected to the twofold stress due 
(1) to the direct compression of the load, and (2) to 
the bending produced by the load acting with a lever- 
arm about the neutral axis of the section. The 
column will completely fail at the point where this 
twofold stress exceeds the crushing-strength of the 
material. This load at failure depends on (1) the 
strength of the material of the column; (2) the value 
of E\ (3) the character of the ends, whether square or 
round; (4) the condition of application of the load, 
whether eccentric or not; and (5) on the ratio of the 
length / of the column to its radius of gyration r. 

In the case of very long columns {l/r > 150) the 
maximum load is that which will hold the column at 
any given deflection, and which, when allowed to con- 
tinue acting, will so increase the deflection as to cause 
failure. This breaking load is given by the equation 

P = uEI -T- /, 

where P= total load at point of flexure; 
E = modulus of elasticity; 
/= moment of inertia; 

/ == length of specimen at point of flexure in 
inches; 
and u = a constant. 

This equation is known as Euler's formula, and the 
values of u are 4 and I for square and round ends, 
respectively. 

The specimens used ordinarily will not be long 
enough to come under this head. For the ordinary 
length of specimen the load on the scale-beam will 



108 ENGINEERING LABORATORY PRACTICE. 

increase with an increasing deflection of the column 
until the twofold stress, mentioned above, will exceed 
the crushing strength of the material. At this point 
the maximum load is indicated, and after this the 
scale-beam drops off with increasing deflection. 

For all ordinary cases this load is given by the 
Rankine-Gordon formula, or by some one of the 
other well-known formulae (as, for instance, Prof. J. 
B. Johnson's parabolic formula) which are intended 
to represent the results of experiments on columns. 

It is necessary in testing columns to define as accu- 
rately as possible the condition of the ends. They 
should be either completely fixed or perfectly free to 
turn. The first condition is difficult to obtain. The 
second condition may be obtained by the use of clamps 
with attached knife-edges, the column being so fitted 
to the clamps that the neutral plane, when the column 
is unstrained, coincides with a plane joining the knife- 
edges. The perfection of the adjustment may be 
tested with moderate loads. 

Specific Directions. — The aim of the laboratory ex- 
periments with columns is to fix in the student's mind 
the behavior of columns of varying lengths. Select a 
piece of 2 X 4-inch wooden scantling and cut it into 
lengths of 86.7, 57.8, 43.35, 21.67, arj d 6 inches. 
Stretch a fine wire along the length of the specimen 
in the plane of the neutral axis. Test these pieces in 
compression with round ends, noting at suitable inter- 
vals of loading the lateral deflection at the neutral 
plane from the wire stretched along the column, and 
the maximum load. The deflection may be read from 
a small scale fixed to the center of the column. In 



STRENGTH OF MATERIALS. 109 

the case of the 6-inch specimen use the compressom- 
eter. 

Plot the results as a curve showing the relation 
between /-— r and maximum scale-beam load for the 
different columns. Compare the results of experi- 
ments with the values derived by calculation from 
various formulae supplied by the instructor. 

100. Cross-bending Tests. — Cross-bending tests 
are used to determine, in case of brittle materials like 
cast iron, the modulus of rupture and the resilience, 
and in case of ductile materials like wrought iron and 
soft steel, the elastic limit and modulus of elasticity. 
Other tests on springs, rails, rail-joints, etc., deter- 
mine the stiffness, i.e., the deflection at given loads, 
the elastic limit, and, in some cases, the ultimate 
strength. Tests on composite structures, like brake- 
beams, truck-bolsters, etc., are made to determine the 
stiffness, the elastic limit, and manner of failure, 

Specific Directions. — In preparing a specimen for 
test (supposing the specimen to be a prismatic beam) 
stretch a fine copper or steel wire between two pins 
which are driven directly above the points of support 
on the line of intersection of the neutral plane with 
the side of the beam. A suitable weight should be 
hung on the wire to keep it taut. Fix a micrometer 
on the beam so as to read the deflection of the 
neutral plane below the fixed wire. Connect the 
micrometer in circuit so that the contact of the 
micrometer with the wire is indicated by the ringing 
of an electric bell consequent on the completion of 
the circuit. In case of large wooden beams, a polished 
steel scale may be attached to the side of the beam at 
mid-span, and the deflection read by eye to hundredths 



IIO ENGINEERING LABORATORY PRACTICE. 

of an inch, taking care to avoid parallax by reading 
when the wire is in coincidence with its image on the 
polished surface. The deflection should not be read 
with reference to any part of the frame of the ma- 
chine. The specimen must be protected if necessary 
from the indentation of the knife-edges by the use of 
bearing-plates. 

Measure the beam in all dimensions and length of 
span. Place the beam so that one principal axis of 
inertia of the section shall be horizontal. Compute, 
for the case of a prismatic beam, the probable center 
load at the elastic limit from the formula 



le 



where R is the value of the elastic limit in tension, 7* 
the moment of inertia, / the length of span in inches, 
and e the distance in inches from the neutral axis to 
the outermost fiber. Divide this load into ten equal 
parts, and apply these part loads successively as in- 
crements to the center of the specimen, endeavoring 
to read the deflection without stopping the test. 
Note the load at rupture and manner of failure. 
Note any side buckling. In some cases the load 
may be released after each increment in order to 
determine the set. 

The Report should include a diagram whose 
abscissae are the deflections, and whose ordinates 
are the loads at the center. The results derived should 
be, when possible to obtain them, stress in outer fiber 
at elastic limit, modulus of rupture, modulus of elas- 
ticity, and resilience- 



STRENGTH OF MATERIALS. Ill 

The modulus of rupture is the value of R as com- 
puted from the formula 

In consequence of the tendency to equalization of 
the stress over the cross-section above the elastic limit 
and of the failure of Hooke's law, the value of R 
determined from this formula (which is based on 
Hooke's law) will in some cases be greater than the 
ultimate strength of the material in tension of steel. 

The elastic limit in flexure will be fixed by the 
elastic limit of the outer fiber, and can be computed 
by the formula given above, assuming that a small 
longitudinal bar in the surface of the beam behaves 
just as it would if tested by itself in tension. The 
elastic limit in flexure will, however, be greater than 
in tension for the case of square or flat plates of steel. 

The ultimate resilience of a brittle material (where 
the elastic limit is near the ultimate strength) will be 

P being the load at the center, and d the deflection 
at that load. E is computed from the formula 

E = 



48 dr 

101. Cement-testing. — The usual tests applied to 
cement are those for tensile strength, fineness, 
soundness, time of initial and final set, and crushing 
strength. 



112 ENGINEERING LABORATORY PRACTICE. 

Specific Directions. — The work will include tests on 
two Portland cements and two natural cements. In 
order to obtain uniform and representative results for 
the tensile strength great care must be exercised to 
observe the following directions: 

(i) Portland Cement. — (a) Neat Tests. — Arrange 
moulds, oiled inside, on a non-absorptive plane sur- 
face. Take i£ pounds of cement and 25 per cent of 
water at 70° F. Mix water and cement thoroughly, 
using enough water to make a stiff plastic mixture, 
and work mixture at least three minutes. Put mix- 
ture in moulds, pressing it firmly in moulds with 
thumbs, but do not pound the briquette. Strike off 
both surfaces of briquette with trowel. Set the 
moulds away on a non-absorptive surface in a damp 
atmosphere. Except for one-day tests they should 
be kept in moist air 24 hours and then put under 
water. The student will return on the following day 
to immerse the briquettes, writing with lead-pencil 
the number of the series on each briquette. 

(b) 2-to-i Mortar Tests. — Take some of the labora- 
tory sand and sift it through Nos. 20 and 30 sieves. 
Use 1 pound of what passes No. 20 and is held on 
No. 30, with \ pound of cement. Mix thoroughly 
and add 15 per cent of water. Work at least 4 
minutes. Fill moulds to overflowing and pound down 
mortar with flat side of trow T el, beginning at sides of 
briquette. These briquettes are disposed of as in 
(I, a). 

(2) Natural Cement. — Take 1^ pounds of cement 
and 30 per cent of water and mix briquettes as di- 
rected in (1, a). Do not allow the cement to assume 
initial set before filling the moulds. Then take J 



STRENGTH OF MATERIALS. 113 

pound of cement and f pound of sand and mix as in 
(1, b). These briquettes may be immersed in water a 
few hours after hardening. 

(3) Concrete. — Concrete should be a compact mass 
as free as possible from pores or open spaces. The 
materials — broken stone, or gravel, and sand — are 
bound together by the cement. The proportion of 
the three different materials should be selected so 
that the sand practically fills the voids in the gravel or 
broken stone and the cement fills the voids in the 
sand. Rather more than this quantity of cement 
should be used to allow for imperfect mixing. 

Fill a box holding one cubic foot with gravel. 
Shake down well and strike off level. Weigh box and 
contents. Then pour water on gravel until the water 
rises to the surface. Weigh again and calculate the 
percentage of voids in the gravel. Then determine 
the weight of a solid cubic foot of sand. Supposing 
the weight of a solid cubic foot of sand to be 165 
pounds, calculate the per cent of voids in the sand. 

Now make a mixture of gravel, sand, and Portland 
cement, with minimum amount of water, using enough 
cement to fill the voids. Directions for mixing will 
be supplied by the instructor. 

Make three 4-inch cubes, and allow them to set 
in air one day and in water 2J days. Test in com- 
pression after 28 days. Make another series with the 
proportion 1 sand, 3 gravel, 1 cement, and test as 
before. Report all data obtained, and report the 
character of gravel and sand supplied, noting whether 
or not the surface of the gravel was clean and 
whether the sand was sharp and free from clay or 
loam, 



114 ENGINEERING LABORATORY PRACTICE. 

For Fineness. — If any time remains determine the 
fineness of grinding by sifting £ pound of cement 
through the three sieves Nos. 50, 80, and 100, weigh- 
ing the residue which remains on each. 

For Constancy of Volume or "Soundness." — Make 
on a slab of glass two thin-edged briquettes, 3 inches 
in diameter and \ inch thick, of stiff plastic consist- 
ency. After thorough setting put one cake under 
water and examine it from day to day to detect any 
radial cracks or changes of form. Do not confuse 
these with the irregular surface-checks which appear 
when the cement is mixed too wet. 

For Portland cements a more severe test is the heat 
test, conducted as follows: expose a pat of neat 
cement, after setting, to the action of steam for several 
hours, then place it in boiling water for three hours 
more. 

Perhaps the best test for soundness is the boiling 
test, as follows: Make two balls \\ to 2 inches in 
diameter and allow them to set in damp air for 24 
hours. Place these in a beaker filled with water and 
bring to boiling-point in 30 minutes. Boil for three 
hours. The test-pieces are examined after slow cool- 
ing. They should not show cracks nor should they 
warp. In case of natural cements these tests are not 
so satisfactory. 

This test is made to detect the presence of free 
lime, the future slaking of which will destroy the 
work into which such cement enters. 

Time of Setting. — Mix pats similar to those for the 
test for soundness. When a needle T ^ inch in 
diameter loaded with \ pound ceases to penetrate the 
entire mass, setting is said to have begun. When a 



STRENGTH OF MATERIALS. 1 1 5 

needle -^ inch in diameter loaded with I pound will 
not penetrate the mass at all, setting is said to be 
complete. The time of complete setting may roughly 
be determined by the fact that the cement offers con- 
siderable resistance to indentation with the finger-nail. 

After One Week, — Test briquettes in tension as 
soon as taken from water, noting the breaking-load in 
the laboratory record. Apply stress at the rate of 
400 pounds per minute. Insert pieces of rubber 
bands between briquette and edges of grips in order 
to obtain break in center of briquette. 

Crushing Strength. — It is not usual to make com- 
pression tests in America. The results in tension vary 
directly with those in compression, so that the tensile 
strength is a satisfactory index of the value of the 
cement in compression. The student will make one 
2-inch cube of each series mentioned and test in com- 
pression after one week as directed in Section 98. 

102. Wire Rope in Tension. — Preparation of Speci- 
men. — In preparing specimens of wire rope for tension 
tests the chief difficulty is to so hold the ends that the 
strain may come equally on all parts of the cross-section 
and a break in the middle of the specimen length may 
occur. By the use of very long conical wedges, 
working in steel bushings, satisfactory results may be 
obtained; the wedges grip the rope as a whole. Or 
an artificial socket may be made in the steel bushing 
as follows: 

Bind the specimen with wire about six inches from 
the ends, to prevent unwinding, and wind the inter- 
vening length with cord to keep the strands in place. 
Slip the bushing over the ends. Unwind the strands 
down to the binding-wire; cut out the hemp core if 



Il6 ENGINEERING LABORATORY PRACTICE. 

necessary, and turn each separate wire back on itself 
toward the center to form a conical head, which may 
be drawn into the bushing so that it may assume 
the proper shape. The head should be boiled in 
caustic soda to remove grease, then washed in hot 
water, dipped in chloride of zinc and afterwards in 
molten solder. The head is then drawn into the bush- 
ing and melted Babbitt metal poured around it. For 
cables of small strength lead may be used in place of 
Babbitt. A method of testing which gives satis- 
factory results is that in which a number of the wires 
are tested individually to determine the uniformity of 
the rope. 

103. Rattler Test for Paving-bricks. — Paving- 
bricks are tested for durability by placing them in a 
rattler of suitable form and noting the amount of wear 
when revolved at a given rate of speed. The results 
from the machine give a true index of the essential 
properties of paving-bricks, namely: toughness and 
vitrification. The machine should be constructed 
according to the dimensions recommended by the 
National Brick Manufacturers' Association. The 
charge should be the number of bricks nearest to 10 
per cent of the volume of the cylinder of the rattler. 
At times a mixed charge of brick and foundry shot is 
used. 

It is found that the diameter of 28 inches and a 
charge of 10 per cent of the volume will give the maxi- 
mum wear. The wear of a brick during the first part 
of a test is due to the chipping of each brick into a 
rounded mass; after that the wear proceeds steadily. 
The test should continue long enough to include the 
effect of the wear beyond the chipping stage; 2000 



STRENGTH OF MATERIALS. 117 

revolutions will accomplish this purpose. It is found 
that beyond a minimum of 18 inches the length of 
the rattling-chamber makes no difference in the 
proportion of wear when the per cent of charge is the 
same, and that, within limits, the rate of revolution 
makes little difference ; 24 to 36 R.P.M. may be used. 
A machine is in use in the Purdue Laboratory which 
conforms closely to the dimensions given above. It 
differs from the ordinary tumbler in the provision 
for inserting brick in the end, thus avoiding the neces- 
sity of removing a slat. The special experimental 
work will be assigned to the student by the instructor. 
104. Impact Tests.— The method of conducting 
impact tests has not been standardized, nor is there 
any uniformity in the construction of machinery for 
such tests. The difficulty in such tests is to so 
arrange the impact that the entire energy of the blow 
may be used in deforming the specimen. Part of the 
energy may disappear in: 

(1) Deforming the specimen locally at the point of 
impact. The loss of energy depends on the relative 
inertia of the moving weight and the specimen, and 
on the velocity of impact. 

(2) In moving the abutments, which may not be 
rigid and will absorb energy 

(3) A small amount of energy may disappear in 
vibration. 

It may be said in general that impact must result 
from the fall of a large weight through a small dis- 
tance, and that the abutments must be solid, or of 
such character that a known amount of energy will be 
absorbed. The specimen must be broken with a 
single blow. 



Il8 ENGINEERING LABORATORY PRACTICE. 

The experimental work assigned will consist of 
experiments on longitudinal impact of wire specimens. 
As no standard form of impact machine has yet been 
prescribed, a machine has been designed for use in 
the Purdue Laboratory which meets the requirements 
mentioned. The apparatus consists principally of a 
framework of two upright posts bridged over at a cer- 
tain height above the floor, a lifting mechanism to 
raise the weight and the specimen, and a revolving 
drum on which the record of the motion of the weight 
is taken. The specimen is attached at its upper end 
to a cast-iron cross-head which slides on ways fastened 
to the posts; to its lower end is attached the weight. 
The specimen with cross-head and weight attached is 
raised to a certain height, and in falling the cross- 
head strikes a cross-piece on the frame which arrests 
its motion suddenly. The specimen sustains the im- 
pact due to the continued motion of the weight. 
The weight consists of a cylindrical casting of 845 
pounds with hollow center to receive the bushing 
or grip. The apparatus is used in the following 
manner: 

Specific Directions. — Take a specimen of Norway 
iron T 5 ¥ inch in diameter and about 10 feet long and 
mark it off in one-foot lengths. Measure its diam- 
eter. Run one end through the cylindrical weight 
and fasten the wire in the steel bushing with the 
conical wedges. Drive the wedges in tight. Draw 
the bushing up inside the cast-iron cylinder until 
it bears against the interior shoulder. Pass the 
upper end of the wire through the cross-bridge 
into the upper bushing. Drive the upper wedges. 
Release the weight so that it is supported by the 



STRENGTH OF MATERIALS. 



II 9 



bridge through the specimen and the upper steel 
bushing. Allow the pencil, attached to the weight, 
to mark the zero-line on the drum. Then arrange the 
pencil so that it will be sure to trip at the proper time. 
Attach the tongs to the upper bushing and lift 
the weight, specimen and upper bushing about 8 feet. 
Wind up the propelling-cord on the drum and at a 
signal from the operator release the drum. When 




Fig. 37. 



the small weight whose descent turns the drum strikes 
the floor, the vibrating tuning-fork is turned on 
the drum and the tongs released. The weight 
descends and fracture of the specimen occurs; the 
pencil, shot out at the proper time, marks a record on 
the drum. Repeat the test on another specimen. 
The drum-record will be about as shown by Fig. 37. 
The energy expended in breaking the specimen will 

be J TdX 

where GX = J* TdX + \M{y? - vf) 9 



120 



ENGINEERING LABORATORY PRACTICE. 



in which G = weight of hammer; 
T= tension in specimen; 
X == total elongation; 
M = mass of G\ 
v x = final velocity; 
z> = initial velocity. 
Divide this energy, in foot-pounds, by the volume 
of the wire in cubic inches and the ultimate resilience 




Fig. 38. 

in foot-pounds per cubic inch will result. Determine 
the time of impact given by the horizontal projection 
of ab. Compare the elongation measured on the 
specimen with the elongation recorded on the drum. 
Measure the diameter of contracted area. Determine 
the velocity of the drum from the tuning-fork record. 
From the known masses and the curve ab construct n 
stress-strain diagram for the specimen as in Fig. 38. 

Divide ac into ten parts, and erect ordinates to meet 
the curve in points p y /, etc. Find the successive 
velocities at these points graphically, i.e., lay off 



STRENGTH OF MATERIALS. 121 

length mn proportional to u, the velocity of the drum, 
and draw from m lines parallel to tangents at p, p\ 
etc. These parallels to the tangents will cut off from 
no lengths which, taken to scale, are the velocities of 
the weight at/, p' , etc. 

Lay these velocities off on the ordinates a'p' , a"p" , 



A 



v 



etc. The acceleration at any point p is -r-, and 

should be computed. 

Then if T is the tension in the specimen, 

T= G + Mp, 

where / is the acceleration. 

Compute the successive values of T and lay these 
off from the axis of elongation ad along d n e" , etc. 
Join the points with a curve, and determine the work 
done, or resilience, as measured by the area between 
the " load-elongation curve," and axis ad. Test 
two similar specimens in the 300,000-lb. Riehle 
machine as directed in Sections 93 and 102. 

Report comparison of results in impact and tension 
as to ultimate stress, total elongation, elongation in 
that foot containing ruptured section, and total 
resilience. 

105. Cold-bending Test. — The following test is 
often prescribed for boiler and similar material: The 
material shall bend double without showing cracks or 
flaws, both while cold and after being heated to a 
cherry red and cooled in water at 8o° F. 

The specimen may be partly bent in a vise and 
afterwards closed down flat in a testing-machine. In 
case an interior radius is specified, an auxiliary plate 
must be dressed to this radius and inserted. The 



122 ENGINEERING LABORATORY PRACTICE. 

specimen should bend without initial cracks or rough- 
ness which will start larger cracks. Rivet-metal is 
commonly tested by cold bending at a nicked section. 
The bar should have one deep nick, not a number 
of successive shallow nicks. The test indicates the 
toughness of the material. 

106. Drifting Tests. — In the drifting test a hole 
is punched or drilled near the edge of a plate and then 
enlarged by a drift-pin. This test, like the cold bend, 
indicates the ductility of the metal. 



CHAPTER X. 
STEAM-BOILER TESTING. 

107. Objects of the Test. — Among the objects 
commonly sought in testing boilers are the following: 
To determine the capacity and efficiency of a given 
boiler under a given set of conditions, to determine 
the change of efficiency of a boiler under different 
conditions, and to determine the amount of coal and 
water necessary to supply a given engine with steam. 

The method employed in making the tests will vary 
in its details to suit the particular object in view. 
The general principles underlying the various methods 
are, however, much the same. 

108. Comparison of Tests under Different Condi- 
tions. — The evaporative or commercial efficiency of 
any given boiler under a given set of conditions is 
usually expressed as the number of pounds of water 
evaporated per pound of dry coal. If the conditions of 
operation remain the same, this forms a just basis for 
the comparison of different boilers. If, however, the 
conditions of operation, such as the steam-pressure or 
the feed-temperature, are not the same, this basis of 
comparison is not suitable, since it requires more heat- 
units to evaporate a pound of water at the higher 
steam-pressure or the lower feed-temperature. 

To secure a fair basis of comparison under all con- 

123 



124 ENGINEERING LABORATORY PRACTICE. 

ditions, it is customary to reduce the actual evapora- 
tion per pound of dry coal to an equivalent evaporation 
per pound of dry coal from a feed-temperature of 
2 12° F. into steam at the same temperature, i.e., at 
atmospheric pressure. This is commonly called the 
equivalent evaporation "from and at 212 F." 

109. Horse-power of Boilers. — The accepted defi- 
nition of a boiler horse-power is the evaporation of 30 
pounds of water per hour from a feed-temperature of 
100 F. into steam at 70 pounds pressure. This is 
equivalent to the evaporation of 34^- pounds per hour 
from and at 212 F. 

110. Boiler Efficiencies. — The efficiency of a boiler 
is usually expressed as the ratio of the heat supplied 
the boiler in the form of coal to that delivered by 
the boiler in the form of steam. This evidently 
includes both the efficiency of the boiler proper and 
that of the furnace. Properly speaking, the efficien- 
cy of the boiler is the ratio of the heat supplied as 
coal minus that lost in the ash, cinders, and waste gases 
to the heat delivered in the steam. The efficiency of 
the furnace is, then, the ratio of the heat supplied as 
coal to that absorbed by the boiler. 

In finding either of these efficiencies, determination 
must be made of the heating value of the coal and of the 
temperature and chemical composition of the waste 
gases. Such determinations are only undertaken in 
connection with the more elaborate tests of boilers. 

in. Determination of Heating Value of Fuels. — 
The determination of the heating-value of fuel is made 
by burning a known weight of the material and 
measuring the heat evolved. The method of burning 
must be such as to produce perfect combustion. The 



STEAM-BOILER TESTING. 125 

fuel may be burned in air or in the presence of oxygen 
or some oxide. The measurement of heat is usually 
made by absorbing it in a known weight of water and 
noting the resulting rise in temperature. From this 
and the constants of the apparatus employed, the heat 
produced can be determined. 

For determining the heating-value of coal, the in- 
struments used are known as coal-calorimeters. They 
are made in a variety of forms, for description of which 
the reader is referred to the various papers and arti- 
cles on the subject.* In selecting the sample of coal 
care should be taken to insure a representative sample. 
A good method of procedure is to draw off a shovel- 
ful from time to time during the conduct of the test, 
the intervals being such as to secure a sample weigh- 
ing from 75 to 100 pounds. Immediately upon the 
clo&e of the test this should be broken up to about 
egg size, carefully mixed and quartered. The quarter 
selected should then be broken to nut size and again 
mixed and quartered. The final quarter should be 
broken to pea size, and placed in an air-tight jar to 
await the calorimetric determination. 

112. Flue-gas Analysis. — In order to ascertain the 
degree of perfection attained in the combustion of 
fuel, recourse is had to the analysis of the flue-gases, 
the results of which serve to indicate the character of 
the combustion. The method of obtaining the sample 
and of analyzing the gases may be found by reference 
to the existing works upon the subject. f 

* Trans. A. S. M. E,, vol. xiv, p. 8r6 and vol. xvi, p. 1040. Car- 
penter's i4 Experimental Engineering," Chap. 14. 

f Hempel's " Method of Gas Analysis," Trans. A. S. M. E., vol. 
VI., p. 786. Carpenter's " Experimental Engineering," Chap. 14. 



126 ENGINEERING LABORATORY PRACTICE. 

113. Graphical Logs. — The graphical log is useful 
in determining the constancy of the conditions under 
which the test was made. It is plotted from the 
running log of the test, taking time as the abscissae 
and the various observed quantities as the ordinates, 
using a suitable scale for each. In case the test is 
made in connection with an engine test, the graphical 
log may be made to include the observations for both. 

114. Methods of Testing Boilers — Following is 
the code of rules for testing boilers prescribed by the 
American Society of Mechanical Engineers, adopted 
at their 1884 meeting: * 

CODE OF RULES FOR BOILER TESTS. 
PRELIMINARIES TO A TEST. 

I. In preparing for and conducting trials of steam- 
boilers the specific object of the proposed trial should 
be clearly defined and steadily kept in view. 

II. Measure and record the dimensions, position, 
etc., of grate- and heating-surfaces, flues and chim- 
neys, proportion of air-space in the grate-surface, kind 
of draught, natural or forced. 

III. Put tlie boiler in good condition. Have heating- 
surface clean inside and out, grate-bars and sides of 
furnace free from clinkers, dust and ashes removed 
from back connections, leaks in masonry stopped, and 
all obstructions to draught removed. See that the 
damper will open to full extent, that it may be closed 
when desired. Test for leaks in masonry by firing a 
little smoky fuel and immediately closing damper. 
The smoke will then escape through the leaks. 

* Trans. A. S. M, E., vol. vi, p. 676. 



STEAM-BOILER TESTING. 12J 

IV. Have an understanding ivith the parties in 
whose interest the test is to be made as to the char- 
acter of the coal to be used. The coal must be dry, 
or, if wet, a sample must be dried carefully and a 
determination of the amount of moisture in the coal 
made, and the calculation of the results of the test 
corrected accordingly. 

Wherever possible, the test should be made with 
standard coal of a known quality. For that portion 
of the country east of the Allegheny Mountains good 
anthracite egg coal or Cumberland semi-bituminous 
coal may be taken as the standard for making tests. 
West of the Allegheny Mountains and east of the 
Missouri River Pittsburg lump coal may be used.* 

V. In all important tests a sample of coal should be 
selected for chemical analysis. 

VI. Establish the correctness of all apparatus used 
in the test for weighing and measuring. These are: 

1. Scales for weighing coal, ashes, and water. 

2. Tanks, or water-meters for measuring water. 
Water-meters, as a rule should only be used as a check 
on other measurements. For accurate work, the 
water should be weighed or measured in a tank. 

3. Thermometers and pyrometers for taking tem- 
peratures of air, steam, feed-water, waste gases, etc. 

4. Pressure-gages, draught-gages, etc. 

VII. Before beginning a test, the boiler and chim- 
ney should be thoroughly heated to their usual work- 
ing temperature. If the boiler is new, it should be 

* These coals are selected because they are about the only coals 
which contain the essentials of excellence of quality, adaptability 
to various kinds of furnaces, grates, boilers, and methods of 
firing, and wide distribution and general accessibility in the 
markets, 



128 ENGINEERING LABORATORY PRACTICE. 

in continuous use at least a week before testing, so as 
to dry the mortar thoroughly and heat the walls. 

VIII. Before beginning a test, the boiler and con- 
nections should be free from leaks, and all water 
connections, including blow- and extra feed-pipes, 
should be disconnected or stopped with blank flanges, 
except the particular pipe through which water is to 
be fed to the boiler during the trial. In locations 
where the reliability of the power is so important that 
an extra feed-pipe must be kept in position, and in 
general when for any other reason water-pipes other 
than the feed-pipes cannot be disconnected, such 
pipes may be drilled so as to leave openings in their 
lower sides, which should be kept open throughout 
the test as a means of detecting leaks, or accidental or 
unauthorized opening of valves. During the test the 
blow-off pipe should remain exposed. 

If an injector is used it must receive steam directly 
from the boiler being tested, and not from a steam- 
pipe or from any other boiler. 

See that the steam-pipe is so arranged that water 
of condensation cannot run back into the boiler. If 
the steam-pipe has such an inclination that the water 
of condensation from" any portion of the steam-pipe 
system may run back into the boiler, it must be 
trapped so as to prevent this water getting into the 
boiler without being measured. 

STARTING AND STOPPING A TEST. 

A test should last at least ten hours of continuous 
running, and twenty-four hours whenever practicable. 
The conditions of the boiler and furnace in all respects 
should be, as nearly as possible, the same at the end 



STEAM-BOILER TESTING. 1 29 

as at the beginning of the test. The steam-pressure 
should be the same, the water-level the same, the fire 
upon the grates should be the same in quantity and 
condition, and the walls, flues, etc., should be of the 
same temperature. To secure as near an approxima- 
tion to exact uniformity as possible in conditions of 
the fire and in temperatures of the walls and flues, the 
following method of starting and stopping a test 
should be adopted: 

X. Standard Method. — Steam being raised to the 
working pressure, remove rapidly all fire from the 
grate, close the damper, clean the ash-pit, and as 
quickly as possible start a new fire with weighed wood 
and coal, noting the time of starting the test and the 
height of the water-level while the water is in a 
quiescent state, just before lighting the fire. 

At the end of the test remove the whole fire, clean 
the grates and ash-pit, and note the water-level when 
the water is in a quiescent state; record the time of 
hauling the fire as the end of the test. The water- 
level should be as nearly as possible the same as at 
the beginning of the test. If it is not the same, a 
correction should be made by computation, and not 
by operating pump after test is completed. It will 
generally be necessary to regulate the discharge of 
steam from the boiler tested by means of the stop- 
valve for a time while fires are being hauled at the 
beginning and at the end of the test, in order to keep 
the steam-pressure in the boiler at those times up to 
the average during the test. 

XI. Alternate Method. — Instead of the standard 
method above described, the following may be em- 
ployed where local conditions render it necessary: 



130 ENGINEERING LABORATORY PRACTICE. 

At the regular time for slicing and cleaning fires 
have them burned rather low, as is usual before 
cleaning, and then thoroughly cleaned; note the 
amount of coal left on the grate as nearly as it can be 
estimated; note the pressure of steam and the height 
of the water-level — which should be at the medium 
height to be carried throughout the test — at the same 
time; and note this time as the time of starting the 
test. Fresh coal which has been weighed should now 
be fired. The ash-pits should be cleaned at once after 
starting. Before the end of the test the fires should 
be burned low, just as before the start, and the fires 
cleaned in such a manner as to leave the same amount 
of fire, and in the same condition, on the grates as at 
the start. The water-level and steam-pressure should 
be brought to the same point as at the start, and the 
time of the ending of the test should be noted just 
before fresh coal is fired. 

DURING THE TEST. 

XII. Keep the Conditions Uniform. — The boiler 
should be run continuously, without stopping for 
meal-times or for rise or fall of pressure of steam due 
to change of demand for steam. The draught being 
adjusted to the rate of evaporation or combustion 
desired before the test is begun, it should be retained 
constant during the test by means of the damper. 

If the boiler is not connected to the same steam- 
pipe with other boilers, an extra outlet for steam with 
valve in same should be provided, so that in case the 
pressure should rise to that at which the safety-valve 
is set, it may be reduced to the desired point by 
opening the extra outlet without checking the fires. 



STEAM-BOILER TESTING. I3I 

If the boiler is connected to a main steam-pipe with 
other boilers, the safety-valve on the boiler being 
tested should be set a few pounds higher than those 
of the other boilers, so that in case of a rise in pressure 
the other boilers may blow off, and the pressure be 
reduced by closing their dampers, allowing the damper 
of the boiler being tested to remain open, and firing 
as usual. 

All conditions should be kept as nearly uniform as 
possible, such as force of draught, pressure of steam, 
and height of water. 

The time of cleaning the fires will depend upon the 
character of the fuel, the rapidity of combustion, and 
the kind of grates. When very good coal is used 
and the combustion not too rapid, a ten-hour test may 
be run without any cleaning of the grates other than 
just before the beginning and just before the end of 
the test. But in case the grates have to be cleaned 
during the test, the intervals between one cleaning 
and another should be uniform. 

XIII. Keeping the Records. — The coal should be 
weighed and delivered to the fireman in equal por- 
tions, each sufficient for about one hour's run, and a 
fresh portion should not be delivered until the previous 
one has all been fired. The time required to consume 
each portion should be noted, the time being recorded 
at the instant of firing the first of each new portion. 
It is desirable that at the same time the amount of 
water fed into the boiler should be accurately noted 
and recorded, including the height of the water in the 
boiler, and the average pressure of steam and tem- 
perature of feed during the time. By thus recording 
the amount of water evaporated by successive portions 



132 ENGINEERING LABORATORY PRACTICE. 

of coal, the record of the test may be divided into 
several divisions, if desired, at the end of the test, 
to discover the degree of uniformity of combustion, 
evaporation, and economy at different stages of the 
test. 

XIV. Priming Tests. — In all tests in which accuracy 
of results is important, calorimeter tests should be 
made of the percentage of moisture in the steam or 
of the degree of superheating. At least ten such 
tests should be made during the trial of the boiler, or 
so many as to reduce the probable average error to 
less than one per cent, and the final records of the 
boiler-test corrected according to the average results 
of the calorimeter tests. 

On account of the difficulty of securing accuracy in 
these tests the greatest care should be taken in the 
measurements of weights and temperatures. The 
thermometers should be accurate to within a tenth of 
a degree, and the scales on which the water is weighed 
to within one-hundredth of a pound. 

ANALYSIS OF GASES — MEASUREMENT OF AIR-SUPPLY, ETC. 

XV. In tests for purposes of scientific research, in 
which the determination of all the variables entering 
into the tests is desired, certain observations should 
be made which are in general not necessary in tests 
for commercial purposes. These are the measurement 
of the air-supply, the determination of its contained 
moisture, the measurement and analysis of the flue- 
gases, the determination of the amount of heat lost by 
radiation, of the amount of infiltration of air through 
the setting, the direct determination by calorimeter 
experiments of the absolute heating value of the fuel, 



STEAM-BOILER TESTING. 



133 



and (by condensation of all the steam made by the 
boiler) of the total heat imparted to the water. 

The analysis of the flue-gases is an especially valu- 
able method of determining the relative value of 
different methods of firing, or of different kinds of 
furnaces. In making these analyses great care should 
be taken to procure average samples — since the com- 
position is apt to vary at different points of the flue, — 
and the analyses should be intrusted only to a 
thoroughly competent chemist, who is provided with 
complete and accurate apparatus. 

As the determinations of the other variables men- 
tioned above are not likely to be undertaken except 
by engineers of high scientific attainments, and as 
apparatus for making them is likely to be improved in 
the course of scientific research, it is not deemed 
advisable to include in this code any specific directions 
for making them. 

RECORD OF THE TEST. 



XVI. A "log" of the 
properly-prepared blanks, 
follows : 



test should be kept on 
containing headings as 





Pressures. 


Temperatures. 


Fuel. 


Feed-water. 










u 
















^j 


Time. 


u 




• 5P 


< 


S 
















9 




V 

a 


u 


ho 

a 


J2 b£ 


C 
u 


u 
ill 


V 


•a 
S 


B 

od 




en 


s 


u 



■ 




rt 




u 


X 







<u 






XJ 




ja 




n 


(/) 


Q 


td 


PQ 


h 


fe 


c/> 


H 


J 


H 


-) 





























134 



ENGINEERING LABORATORY PRACTICE, 



REPORTING THE TRIAL. 

XVII. The final results should be recorded upon a 
properly prepared blank, and should include as many 
of the following items as are adapted for the specific 
object for which the trial is made. The items marked 
with a * may be omitted for ordinary trials, but are 
desirable for comparison with similar data from other 
sources. 

RESULTS OF THE TRIALS OF A BOILER 

AT TO DETERMINE 



i. Date of trial 

2. Duration of trial 

DIMENSIONS AND PROPORTIONS. 

(Leave space for complete description.) 

3. Grate-surface. . . .wide. . . .long. . . .area 

4. Water-heating surface 

5. Superheating-surface 

6. Ratio of water-heating to grate-surface 

AVERAGE PRESSURES. 

7. Steam-pressure in boiler, by gage 

*8. Absolute steam-pressure .. 

*9. Atmospheric pressure, per barometer.. 
10. Force of draught in inches of water 

AVERAGE TEMPERATURES. 

*n. Of external air 

*I2. Of fire-room 

*I3- Of steam 

14. Of escaping gases 

15. Of feed-water 



* See reference in paragraph preceding table. 



STEAM-BOILER TESTING. 



135 



FUEL. 

f 16. Total amount of coal consumed 

17. Moisture in coal 

18. Dry coal consumed 

19. Total refuse, dry- • ■ .pounds = 

20. Total combustible (dry weight of coal, 

Item 18, less refuse, Item 19) , . . 

*2i. Dry coal consumed per hour 

*22. Combustible consumed per hour 

RESULTS OF CALORIMETRIC TESTS. 

23. Quality of steam, dry steam being taken 

as unity 

24. Percentage of moisture in steam 

25. Number of degrees superheated 

WATER. 

26. Total weight of water pumped into boiler 

and apparently evaporated^: 

27. Water actually evaporated, corrected for 

quality of steam § 

28. Equivalent water evaporated into dry 

steam from and at 212 F.§ 

*29. Equivalent total heat derived from fuel 
in British thermal units § 

30. Equivalent water evaporated into dry 

steam from and at 212 F. per hour 

ECONOMIC EVAPORATION. 

31. Water actually evaporated per pound of 

dry coal, from actual pressure and tem- 
perature § 

32. Equivalent water evaporated per pound of 

dry coal from and at 212 F.§ 

33. Equivalent water evaporated per pound 

of combustible from and at 212 F.§ 



lbs. 
per cent 

lbs. 
per cent 

lbs. 
lbs. 
lbs. 



per cent 
deg. 



lbs. 
lbs. 
lbs. 
B. T. U 
lbs. 

lbs. 

lbs. 
lbs. 



* See reference in paragraph preceding- table. 

+ Including equivalent of wood used in lighting fire. One pound of wood 
equals 0.4 pound coal. Not including unburnt coal withdrawn from fire at end 
of test. 

X Corrected for inequality of water-level and of steam-pressure at beginning 
and end of test. 

§ The following shows how some of the items in the above table are derived 
from others: 

Item 27 = item 26 X item 23; 

Item 28 = item 27 X factor of evaporation; 



136 



ENGINEERING LABORATORY PRACTICE. 



COMMERCIAL EVAPORATION. 

34. Equivalent water evaporated per pound of 
dry coal with one sixth refuse, at 70 
pounds gage-pressure, from temperature 
of ioo° F. = Item 33 multiplied by 0.7249. 

RATE OF COMBUSTION. 



35- 



* 3 6. 

*37- 
*38. 



39- 



Dry coal actually burned per square foot 

of grate-surface per hour 

f Consumption of ^| Per sq. ft. of grate- 
surface 

Per sq. ft. of water- 
heating surface . . . 
Per sq. ft. of least 
area for draught . . 



dry coal per | 
hour. Coal as- I 
sumed with ' 
one sixth ref 
use.f 



RATE OF EVAPORATION. 



Water evaporated from and at 212 F. 

sq. ft. of heating-surface per hour.. 

" Water evapor- 



per 



^40. 
f 42. 



ated per hr. 
from tem- 
perature of 
100 F. into 
steam of 70 
lbs. gage- 
pressure. f 



Per sq. ft. of grate- 
surface 

Per sq. ft. of water- 
heating surface 

Per sq. ft. of least 
area for draught. . . . 



lbs. 

lbs. 
lbs. 

lbs. 
lbs. 

lbs. 

lbs. 
lbs. 
lbs. 



Factor of evaporation = 



H 



965-7 



H and h being respectively the total heat-units 



in steam of the average observed pressure and in water of the average observed 
temperature of feed, as obtained from tables of the properties of steam and water; 

Item 29 = item 27 X (H - A); 

Item 31 = item 27 -r- item 18; 

Item 32 = item 28 -+- item 18 or = item 31 X factor of evaporation; 

Item 33 = item 28 -7- item 20 or = item 32 -=- (per cent 100 — item 19); 

Items 36 to 38. First term = item 22 X f ; 

Items 40 to 42. First term = item 39 X o. 

, A . item qo 
Item 43 = item 29 X 0.00003 or = — ; 

34s 



, _ difference of items 43 and 44 

item 44 



* See note *, p. 134. 



+ See note §, p. 135. 



STEAM-BOILER TESTING. 



»37 



COMMERCIAL HORSE-POWER. 

43. On basis of thirty pounds of water per 

hour evaporated from temperature of 
ioo° F. into steam of 70 pounds gage- 
pressure (=34^ lbs., from and at 2i2°)f. 

44. Horse-power, builders' rating at. . . .sq. ft. 

per horse-power 

45. Per cent developed above, or below, rat- 

ingf 



t See note §, p. 135. 




115. Abbreviated Directions. — Apparatus, — Tanks 
and scales for weighing water, scales for weighing 
coal, calorimeter, barometer, thermometers for tem- 
perature of room, feed-water, and waste gases. 

Method. — Calibrate all apparatus. Prepare blank 
logs and post observers. Note Rules VII and IX 
before starting. Start by standard or alternate 
methods, Rules X and XI. Take readings of time, 
boiler-pressure, barometer, draught, temperature in 
smoke-box, quality of steam, pounds water supplied, 
pounds water lost by calorimeter, leakage, etc., 
pounds coal fired, per cent of moisture in coal, pounds 
dry ash. Observe Rules XII, XIII, and XIV during 
the test. Make test ten hours long if possible, mak- 
ing running observations every ten minutes. If 
possible keep coal and water record so that quantities 
may be computed for each hour. Dry a sample of 
coal, not less than 50 pounds, in order to determine 
per cent of moisture. If using standard method of 
starting and stopping, dump the grates at end of test 
and weigh all the ash, minus any unburned coal, which 



I38 ENGINEERING LABORATORY PRACTICE. 

should be removed, weighed, and the weight deducted 
from the total amount of coal fired. If using the 
alternate method, do not dump the grates until the 
ash is removed and weighed, and do not weigh back 
any unburned coal found on grate or in ash. 

Report. — Make report on forms given and submit a 
graphical log (Section 113) of the test. For method 
of working up the test and calculating the various 
desired results, see Section 161. The method of 
conducting special boiler-tests is given under separate 
heading (Sees. 160 and 162). 



CHAPTER XL 
THE STEAM-ENGINE INDICATOR. 

116. General Description. — The steam-engine in- 
dicator is an instrument used for recording the pressure 
on the engine-piston at each point of its stroke. It 
consists of the following elements: 

The Cylinder and Piston, the former in pipe connec- 
tion with one end of the engine-cylinder in such a 
manner that the pressures in the latter are received 
by the indicator-piston. 

The Indicator-spring, attached to the piston and 
opposing the force of the steam-pressure, allowing a 
limited motion, proportional to that pressure. 

The Pencil-motion, by which the motion of the 
piston is multiplied, the resultant motion of the pencil 
being a straight line. 

The Drum, which gives motion to a card in direct 
proportion to the motion of the engine-piston, but of 
a total length usually not exceeding four inches. The 
drum is actuated by a cord of braided linen and its 
motion is controlled by a spring, the tension of which 
may be varied to suit the speed. 

117. The Crosby Indicator. — A sectional view of 
the Crosby indicator is shown in Fig. 39. The prin^ 
cipal parts are a piston, 8, moving within the cylinder, 

139 



140 



ENGINEERING LABORATORY PRACTICE. 



4, and connected with the pencil-lever, 16, by means 
of a piston-rod, 10, swivel-head, II, and link, 14. 
The pencil mechanism, by which the pencil, 23, is 




Fig. 39. — The Crosby Indicator. 

caused to move in a straight line, consists of a system 
of links mounted on a sleeve, 3. The motion of the 
piston is resisted by a spring fastened at its lower end 
to the piston by means of a ball-joint and at its upper 
end to a cap, 2, which forms the upper cylinder-head. 
The drum, 24, drum-spring, 31, and connected parts 
are easily understood by reference to the cut. 



THE STEAM-ENGINE INDICATOR. 



141 



To remove the piston and pencil mechanism from the 
indicator, unscrew the cap, 2, and lift the cap, sleeve, 
3, and connected parts from the indicator. 

To insert the spring ', unscrew the piston and piston- 
rod from the swivel-head, holding the cap, 2, from 
turning. Take the socket-wrench from the cover of 
the indicator-box, slip it over the piston-rod, and 
unscrew the latter from the piston. Now with the 
piston-rod still in the socket of the wrench slip the 
spring over the piston-rod until the bead of the spring 
rests in the concave end of the rod ; then invert the 
piston and pass the transverse wire of the spring 
through the slotted portion of the piston-socket and 
screw the piston-rod firmly into place. The lower 
piston-screw, 9, should be loosened slightly before 
this last operation and afterwards set up against the 
bead lightly to prevent lost motion, but not enough to 
prevent the bead from turning. 

Caution. — In the under side of the shoulder of the 
piston-rod B y Fig. 40, is an annular channel formed 




Fig. 40. 



to receive the upper edge of the socket on the 
piston A. When attaching the piston to the rod 
always screw the piston-rod onto the socket as far as 
it will go; that is, until the upper end of the socket, 



142 ENGINEERING LABORATORY PRACTICE. 

d , is brought firmly against the bottom of the annular 
channel, b*, in the piston-rod. This insures correct 
alignment of the piston within the cylinder. 

Having the spring and piston together, hold the 
sleeve and pencil-motion in an upright position, slip 
the piston-rod up over the threaded portion of the 
swivel-head, II, Fig. 39, until the threads on the 
upper head of the spring engage those on the cap, 2, 
and screw the spring firmly onto the cap. Now allow 
the cap to turn and screw the piston-rod onto the 
swivel-head until the top of the rod is nearly flush 
with the shoulder on the swivel-head. The piston 
may now be inserted in the cylinder and the cap 
screwed into place. 

To change the location of the atmosphere- line y un- 
screw the cap and remove the piston, and pencil- 
movement. Unscrew the piston-rod from the swivel- 
head to raise the atmosphere-line and the reverse to 
lower it. One turn will change the position of the 
pencil •§• of an inch. 

To change the drum tension y remove the drum, lift 
the knurled nut at the top of the drum spring from its 
square seat, turn in the direction required, and re- 
place. 

118. The Tabor Indicator. — The special feature of 
the Tabor indicator is the means employed to secure 
a straight-line motion for the pencil. This is secured 
by means of a curved slot, fastened to the cylinder- 
cap, in which travels a roller attached to the pencil- 
lever (Fig. 41). 

The method of fastening the piston, rod, and 
spring together differs from that employed in the 
Crosby indicator in that the point of flexibility 



THE STEAM-ENGINE INDICATOR. 



H3 



occurs, not between the spring and the piston, but 
between the piston and the rod. 

To remove the piston and pencil mechanism from the 
indicator, unscrew the cylinder-cap and lift it with the 
connected parts from the indicator. 

To insert the springy unscrew the small nut under 
the piston from the piston-rod and remove the piston. 




Fig. 41. — The Tabor Indicator. 

Slip the spring over the piston-rod, the end marked 
T uppermost, and screw it to the cap; then screw the 
piston to the lower end of the spring. Now move the 
pencil-motion down until the lower end of the piston- 
rod enters the piston and the square shoulder enters 
the square socket provided in the piston. Holding it 



144 ENGINEERING LABORATORY PRACTICE. 

in this position, replace the small nut below the piston, 
screwing it firmly home. The piston may now be 
replaced in the cylinder and the cap screwed in place. 

To change the drum tension, remove the drum, drive 
out the small taper-pin which holds the knurled nut 
and unscrew the latter. Now grasp the drum-carriage 
firmly, lift it clear of the stops, turn in the required 
direction, and lower into place. Do not loose hold of 
it or the spring will rapidly uncoil and become 
detached. Replace the nut, taper-pin, and drum. 

119. Choice of Spring. — Such a spring should be 
used that the maximum pressure to which it will be 
subjected is not greater than one and three quarter 
times the scale of the spring. Following is a table of 
the scale of spring to be used with different steam- 
pressures: 



Steam-pressure (gage). 


Scale of Spring. 


40 


30 


60 


40 


80 


50 


IOO 


60 


140 


80 


175 


IOO 


2IO 


120 


250 


150 



120. Use of the Indicator. — The indicator is one 
of the most delicate and costly instruments which the 
engineer uses in ordinary practice. It requires careful 
handling and a thorough knowledge of its construction 
and operation in order to secure accurate results and 
prevent damage to itself. 

Before the Test. — Remove the indicator carefully 
from its box, handling it so far as possible by the 



THE STEAM-ENGINE INDICATOR. 145 

cylinder. Never handle an indicator by the drum, as 
this is loose in most makes and comes off readily. 
Lift the pencil up and down slowly to see that it is 
perfectly free. Remove the pencil-motion and piston 
by unscrewing the knurled nut at the top of the 
cylinder. Thoroughly clean all working parts. 

Insert the spring in the pencil-motion as explained 
in Sections 117 and 118. Cover the piston with a 
thin coat of heavy oil and replace in the cylinder. See 
that the moving parts of the drum and pencil-motion 
are lubricated with watchmaker's oil. 

After blowing out the cock with steam, attach the 
indicator to the engine, and adjust the guide-pulleys 
so that when the cord is attached to the reducing- 
motion it will be parallel to the motion of the indi- 
cator-rig or, if a brumbo pulley is used, will be 
tangent to it. Adjust the cord so that the drum will 
not strike either stop when the cord is attached to the 
rig. If a hook is used on the drum-cord a convenient 
mode of attaching it to the cord is to pass the end of 
the latter through the eye of the hook and then make 
two half-hitches around the shank. This hitch may 
be easily untied by slipping it over the end of the 
hook. If the drum tension needs altering it may be 
changed as explained in Sections 117 and 118. 

Taking the Card. — Place the blank card on the 
drum so that both ends will be under the clips and not 
project out from the drum. By so doing the card 
will be less liable to come loose and will lie flat when 
taken. See that the pencil is firmly placed and sharp. 
For very accurate work a brass point should be used 
in connection with iA metallic paper/' Taking the 
loop of cord attached to the reducing-rig in one hand, 



I46 ENGINEERING LABORATORY PRACTICE. 

pull the drum-cord out to the end of its travel several 
times and then attach to the loop. Adjust the pencil- 
pressure to give a fine line. Open the cock half-way 
and allow steam to blow through the relief for two or 
three revolutions, then open full and draw the dia- 
gram. Close the cock, draw the atmosphere-line, and 
unhook the drum, taking care not to let it snap back 
against the stop. Remove the card and examine to 
see if there are any irregularities in the diagram. If 
these appear call the attention of the instructor to 
them. They may be due to disarrangement of parts 
or grit in the indicator-cylinder. If the latter, the 
piston should be removed, the cylinder blown out, 
and the piston oiled and returned. This should be 
done occasionally on all engine-tests. If the indicator 
is used on a gas-engine the piston should always be 
removed from its cylinder when not actually in use, 
as it is liable to be overheated if left on the engine 
between cards. 

After the Test. — Remove the indicator immediately, 
using waste to prevent burning the hands. Remove 
the piston and spring and clean all parts thoroughly. 
Oil the piston and working parts and put together 
without the spring. 

121. Errors of the Indicator. — The two most fruit- 
ful sources of error in the mechanism of the indicator 
are the pencil-motion and the spring. To test the 
former, place a card on the drum and draw the atmos- 
phere-line. With the spring out place the pencil in 
contact with the paper and raise it up to the full 
height of its travel. Repeat at several different 
points on the card, holding the drum firmly in each 



THE STEAM-ENGINE INDICATOR, 



H7 



position. Test the perpendicularity of the lines with 
a triangle and straight-edge. 

122. Testing Indicator-springs. — Indicator-springs 
are often tested under hydraulic pressure and even by 
pressure exerted by a rod upon the under side of the 
piston, the lower end of the rod resting on suitable 
scaler. Most satisfactory results, however, may be 
obtained by a test under steam-pressure, in which case 
the conditions of the test are similar to the conditions 
of actual use, but it has generally been found difficult to 
maintain a constant pressure and to accurately deter- 
mine its value. A steam-gage is too sluggish in action 
to properly serve in this connection. A method of 
testing has been devised by Prof. W. F. M. Goss 
which overcomes these difficulties. The apparatus 
consists of a steam-drum having a pressure-regulating 
valve which responds to change in volume rather than 
to change in pressure, the pressure remaining constant 
at any point desired. The details of the arrangement 
are shown by Fig. 42. 





a rh rTU 




if ■ 


B 


Ad 


i 


■$= 





Fig. 42. — Indicator-testing Apparatus, 



As is clearly shown by this sketch, a piston of 
known area is arranged to receive the pressure in the 
drum, against which it is held by standard weights 
placed upon the holder at its upper end. The piston 



I48 ENGINEERING LABORATORY PRACTICE. 

is free to move between stops, and as it rises it in- 
creases the area of port-opening through which the 
steam within the drum is allowed to escape. The 
piston therefore serves as a means of controlling and 
weighing the pressure within the drum. 

The area of the piston is one fifth of a square inch. 
The piston with weight-holder weighs one pound. A 
pressure of five pounds per square inch may therefore 
be maintained with no weights upon the holder. The 
weights to be used are those supplied with the Crosby 
Gage-tester. The value of these weights (which is 
stamped upon them) is five times their actual weight. 

Specific Directions. — Attach the indicator (or indi- 
cators) by means of the usual indicator-cocks. Open 
wide the discharge-valve D (Fig. 42). Have no 
weights upon the weight-holder, place one hand on 
it, and gradually open the steam-supply valve, 5. 
Thoroughly warm the steam-drum, allowing the 
weight-holder to rise under pressure of the hand. 
Observe the amount of motion which the weight-holder 
has, so that in the work to follow it may not be 
allowed to strike against its stops. Load the weight- 
holder with the desired weight and adjust the steam- 
supply valve, if necessary. Open and close the in- 
dicator-cock several times; finally leave it open; twirl 
the weight-holder, and make the record on the indi- 
cator-card by revolving the drum by hand. Be sure 
that on the ascending scale the pencil rises to the 
pressure and on the descending scale falls to the pres- 
sure, since one object of the test is to discover any 
lost motion or friction which may exist. 

There should be one observer to manipulate the 



THE STEAM-ENGINE INDICATOR. 



149 



testing apparatus and one for each indicator to be 
tested. 

The Record, — Before putting the paper on the 
indicator-drum draw upon it two parallel vertical 
lines about a quarter of an inch apart (a and b y 

Fig. 43)- 

When testing with differences of pressure on the 
ascending scale, make lines by means of the indicator 
toward the right, beginning with the left vertical; 
when the differences of pressure are on the descending 
scale, make lines toward the left, beginning with the 
right vertical. 

For springs under thirty pounds to the inch make 





25 






20 




e 




IS 


/ 


k 


— ? 



O 




10 


ft 




i 


1 


5 






Atmosphere 




Line 


a 




b 



Fig. 43. 
a record for every five pounds change in pressure; for 
springs above thirty pounds, for every ten pounds 
change in pressure. Care should be taken that the 
spring is not subjected to a greater pressure than it is 
made to stand (see Section 119). Take several cards; 
then remove and clean the indicators. 

With a scale corresponding to that of the spring, 
measure the pressures from the atmosphere-line up to 
the several lines drawn, and record the same on their 
respective lines. 

The Report should be made out on the blank form 
given below. Paste the card to the report sheet. 



150 



ENGINEERING LABORATORY PRACTICE. 



123. Form for 

CALIBRATION OF INDICATOR-SPRING NO.... 

IN CONNECTION WITH INDICATOR No. 



Observers X 



SCALE OF SPRING 



Date, 



No. 



Actual 
Pres- 
sure. 


Reading. 


Error. 


Up. 


Down. 


Up. 


Down. 













Remarks. 



Attach card here. 

124. The Indicator-diagram. — The diagram drawn 
by the steam-engine indicator furnishes the means for 
determining the action of the valve, for analyzing the 
action of the steam in the cylinders, and for determin- 
ing the power developed. In Fig. 44 is shown a 
typical diagram taken from a locomotive at speed. 



#Adm, 




Fig. 44. 

The Point of Admission, a, is the point at which the 
valve opens for the admission of steam to the cylinder. 

The Steam line, from a to c~o, is the line drawn 
during the time when the steam is passing into the 
cylinder. 

The Point of Cut-off, c-o, is the point at which the 



THE STEAM-ENGINE INDICATOR. 151 

valve is just closed, the admission of steam ceases, and 
expansion begins. 

The Expansion- curve, from c—o to r, is the line 
drawn while the steam is expanding behind the 
piston. 

The Point of Release, r, is the point at which the 
valve opens communication with the exhaust-port and 
the steam is released from the cylinder. 

The Exhaust-line, from r to c, is the line drawn 
while steam is being exhausted from the cylinder. 
The lower portion is also called the Back-pressure 
Line. 

The Point of Compression, c, is the point at which 
the valve closes communication with the exhaust-port 
and the steam retained in the cylinder begins to com- 
press. 

The Compression-curve ', from c to a, is the line 
drawn while compression is taking place. 

The Initial Pressure is measured from the atmos- 
phere-line to the highest point of the steam-line. Do 
not confuse this with a high point sometimes appear- 
ing just at the beginning of the stroke, due to inertia 
of the moving parts of the indicator. 

The Least Back-pressure is measured from the atmos- 
phere-line to the lowest point of the back-pressure line. 

The Events of Stroke are the points of admission, 
cut-off, release, and compression. 

The Per Cent of Stroke at the different events is the 
distance of the piston from its initial or admission end 
when the event occurs, expressed as a per cent of the 
total length of stroke. 

125. Locating the Events of Stroke. — The loca- 
tion of the events of stroke, especially for cards taken 



152 ENGINEERING LABORATORY PRACTICE. 

at high speed, requires much care and considerable 
skill. In locating, for instance, the point of cut-off, 
the best method is to follow with the eye up the 
expansion-curve until the point is reached at which 
the reverse curve begins. This point may be taken 
as the point of cut-off. Similarly, for release, follow 
down the expansion-curve until the point is reached 
at which the reverse curve leading to the back-pressure 
line begins. This is the point of release. When 
determining these points for the purpose of finding 
the weights of steam, it is essential that the valve be 
entirely closed at the points located. It will therefore 
be found more accurate, when doubt exists as to the 
precise location of the point, to locate it too far on 
the expansion-curve rather than the reverse. Do not 
continue the expansion or compression curves up and 
down, as shown in Fig. 45. This is a common method 
of locating the events, but is apt to obscure the real 
point sought. 




Fig. 45. 

126. Determining the Per Cents of Stroke. 

When the events are located, draw ordinates through 
them and at the ends of the card. Make a scale 
somewhat longer than the longest card, about an 
eighth of an inch, and divide it into one hundred 
parts. If this scale be placed so that the ends exactly 
coincide with the end ordinates, the percentage of 



THE STEAM-ENGINE INDICATOR. 153 

stroke may be read directly for each event and prop- 
erly recorded on the corresponding ordinate. All per- 
cents should be taken from the admission-end of the 
card. 

127. Mean Effective Pressure. — The mean effec- 
tive pressure for one end of the engine is the average 
pressure during the forward stroke on that end, minus 
the average pressure during the return stroke. As 
shown by the card, it is the average length of all the 
ordinates intercepted between the upper and lower 
lines of the card, multiplied by the scale of the spring. 
For rough approximations the M.E.P. may be deter- 
mined from the following formula, neglecting clear- 
ance and compression: 

M.E.P. = (* + hyp, log .£)/>-*/> 

R. 

where R is the ratio of expansion or the piston-dis- 
placement divided by the volume at cut-off, P 1 is the 
initial pressure, and P 2 the back-pressure, absolute. 
The results thus obtained will always be greater than 
the actual values. 

128. Mean Effective Pressure by the Method of 
Ordinates. — First, by use of two triangles draw 
ordinates at each end of each diagram, perpendicular 
to the atmosphere-line. Next construct on a piece 
of paper a scale of ten equal parts such that the sum 
of the parts will be a little greater than the length of 
any of the diagrams. To use this scale place it 
obliquely across the card in such a position that the 
first and last division points will fall on the end ordi- 
nates already drawn. Make points on the card oppo- 
site each division on the scale, and afterwards draw 



1 54 



ENGINEERING LABORATORY PRACTICE. 



ordinates through each of these points. If this work 
be properly done, each diagram will be divided into ten 
vertical sections of equal width (Fig. 46). It remains 



rHNCO-^lOO I. CO © 3 £3 




Fig. 46. 

to obtain the average height of these sections which, 
since the sections constitute the card, may be accepted 
as the average height of the card. Lay off on a strip 
of paper having a straight edge (Fig. 47) the effective 




Fig. 47. 

height of the card as observed on the first ordinate, 
that is, lay off ab (Fig. 46) on the paper strip as a l b x ; 
add to this the height of the last ordinate cd> as b l d l \ 
and then take half the distance a l d l as a new starting 
point e, and add the effective length of all the other 
ordinates making yg* = eg\ hi = g l i\ etc., until all the 
intermediate ordinates are taken off. When this is 
accomplished the distance measured on the strip from 
a 1 to the last point is approximately the sum of the 



THE STEAM-ENGINE INDICATOR. 1 55 

height of the vertical slices, and this distance divided 
by ten (there being ten spaces) will give the average 
height of the card. This average height in inches 
multiplied by the scale of the spring gives the M.E.P. 
of the card. The reason that half the sum of the first 
and last ordinates is taken will appear when it is 
remembered that the result sought is the average 
height of the ten spaces and not of eleven lines. In 
other words, the first and eleventh ordinates are con- 
sidered as the same line, a condition which can be 
illustrated by rolling up the card until they coincide. 

129. Mean Effective Pressure by the Planimeter. 
— The usual method of finding M.E.P. is to measure 
the area of the card with a planimeter (see Sections 1 1 
and 15) and divide the area thus found by the length 
parallel to the atmosphere-line. The quotient, which 
is the height of the mean ordinate in inches, is multi- 
plied by the scale of the spring to give the M.E.P. 
The length of the card is found as follows: Place a 
straight-edge on the card coincident with the atmos- 
phere-line, and with a triangle draw ordinates at each 
end of the card. The length can now be measured to 
hundredths of an inch, holding the scale parallel to 
the atmosphere-line. 

130. Condensed Directions for working up Cards. 
— 1st. Locate the events of stroke, admission, cut-off, 
release, and compression, with great care on all cards. 
Be sure that the last three are well on their respective 
hyperbolic curves. In this connection it should be 
remembered that when doubt exists as to the exact 
location of, for instance, the point of cut-off, much 
less error in calculating the weight of steam at that 
point will result from locating the point too late than 



156 



ENGINEERING LABORATORY PRACTICE, 



the reverse, since after cut-off occurs the change in 
weight is very slight compared with the change 
immediately preceding cut-off. Do not attempt to 
continue the expansion and compression curves up 
and down as in Fig. 45, as this is apt to obscure the 
real location of the event. Submit some of your first 
work to the instructor before proceeding. 

2d. Draw ordinates through the points located 
with a fine hard pencil or, if metallic paper is used, 
with a brass point. Draw them perpendicular to the 
atmosphere-line and about two inches long. 

3d. Draw end ordinates, locating them with great 
care. 

4th. Find areas with the planimeter. These should 
be checked by two men to within one per cent and 




Fig. 48. 

the two readings averaged. Use a smooth board 
covered with a sheet of foolscap to run the planimeter 
on, and see that the record-wheel does not mount the 
card. Do not dig the tracing-point of the planimeter 
into the card and thus destroy its outline. In case 
the card is dim, make fine pencil-points about i inch 
apart around its outline before tracing with the 
planimeter. Enter the result as shown in Fig. 48. 



THE STEAM-ENGINE INDICATOR. I 57 

5th. Measure the length of the card parallel to the 
atmosphere-line, reading to hundredths of an inch. 
This need not be checked. 

6th. Calculate the M.E.P. to two places of deci- 
mals. Do not use a slide-rule for this work. This 
calculation must be checked. In figuring M.E.P., it 
will be found more accurate to multiply the area by 
the scale of spring and then divide by the length. 
This method should be followed. Do not figure on 
the back of the card. 

7th. Measure pressures at cut-off, release, compres- 
sion, and find initial and least back-pressures. These 
should all be taken from the atmosphere-line, and the 
results should be marked on each ordinate as shown 
in Fig. 48. The initial pressure is generally taken as 
the highest point on the card unless there are indica- 
tions that the highest pressure is due to excessive 
compression, indicator inertia, or some cause other 
than initial steam-pressure. 

8th. Measure per cents of stroke at the same points 
and enter on the proper ordinate. These should be 
read to one place of decimals. 

131. Calculations from the Card. Horse-power. 
— The work developed in the cylinder of the engine is 
the product of two factors. The first may be called 
the total mean effective pressure, and is the product 
of the M.E.P. and the net area of the cylinder in 
square inches. The second is the distance through 
which the foregoing pressure is exerted per minute or 
the product of the length of stroke in feet by the 
number of effective strokes per minute. The first 
factor is expressed in pounds, the second in feet per 
minute, and the product, foot-pounds per minute, 



I58 ENGINEERING LABORATORY PRACTICE. 

may be reduced to the equivalent horse-power by 
dividing by 33,000. 

To determine the horse-power of the ordinary 
steam-engine, find the M.E.P. of the cards as ex- 
plained in Section 128 or 129. Average this M.E.P. 
for each end of the cylinder and apply each value in 
the following formula: 

PLAN 



H.P 



33000' 



where P is the M.E.P., L the length of stroke in feet, 
A the net area of the cylinder (on the end in question) 
in square inches, and N the revolutions per minute. 
This will give the horse-power on each end of the 
cylinder. The total indicated horse-power of the 
engine is the sum of that for the two ends. 

132. Use of the Engine Constant. — When the 
horse-power of the engine is to be found under a 
number of different conditions, the calculation may be 
simplified by the use of the engine constant. This 
is a factor which is determined for each end of the 
cylinder and is composed of the constant factors of the 
usual horse-power formula as follows: 

^ . LA 

Engine constant = 



33000 



The horse-power is now found for each end of the 
cylinder by multiplying together the engine constant 
for that end, the M.E.P. for that end, and the 
R.P.M. 

133. Weights of Steam from the Card. — In find- 
ing the steam-consumption from the card and in 
tracing the action of the steam in the cylinder it is 



THE STEAM-Ex\GINE INDICATOR. 1 59 

necessary to find the weight of steam in the cylinder 
at the different events of stroke. The weight of 
steam at any point, as for instance at cut-off, is found 
from the indicator-card on the assumption that the 
cylinder is full of steam that is dry and saturated. 

The factors in the calculation are, first, the volume 
in cubic feet of the space filled with steam at the 
point of cut-off, and second the w T eight of a cubic foot 
of steam at the pressure existing at cut-off. To 
determine the first factor, find the per cent of stroke 
at cut-off and add the per cent of clearance for the 
cylinder-end under consideration. These are both 
expressed as per cents of the piston-displacement, and 
hence if their sum be multiplied by the piston-dis- 
placement in cubic feet, the result will be the volume 
of steam at cut-off. The weight of a cubic foot of 
steam at the absolute pressure of cut-off may be 
found from the Steam Tables, section 182. This, 
multiplied by the volume, will give the weight of 
steam at cut-off by indicator. 

The weights of steam at the other events of the 
stroke may be found in a similar manner. 

It will be seen that inasmuch as a portion of the 
steam in the cylinder is not dry and saturated, but has 
been condensed and exists as water, the weights of 
steam shown by indicator will be in error to this 
extent. 

134. Reevaporation. — As the steam enters the 
cylinder during the period of admission a portion of 
it is condensed by coming in contact with the cooler 
walls and the retained steam. After cut-off occurs 
the temperature of the expanding steam falls below 
that of the cylinder-walls and a portion of the mois- 



6o 



ENGINEERING LABORATORY PRACTICE. 



ture is reevaporated. The amount of this reevapora- 
tion per stroke during expansion is determined by 
subtracting the weight of steam at cut-off from that 
at release. The reevaporation per revolution is the 
sum of the weights per stroke for each end. 

135- Clearance from the Card. — Two methods of 
determining clearance from the indicator-card are 
given below. The methods are both approximate, 
since they are based upon the assumption that the 
expansion and compression curves are hyperbolic 
curves. Since the compression-curve is generally 
nearer an hyperbola than the expansion-curve, it is 
preferably used for this work. 

First Method, — Select two points a and b, Fig. 49, 
on the expansion or compression curve, and draw 




o 9 



f No Pressure Line 
Fig. 49. 



vertical and horizontal lines through each, forming a 
parallelogram having the line joining the points for a 
diagonal. Then the point at which the other diagonal 
produced intersects the line of no pressure will also 
mark its intersection with the clearance-line. The 
distance og in per cent of the whole length of the card 
is the per cent of clearance. 

Second Method. — Draw a line cd through the expan- 
sion or compression curve, Lay off ec equal to df. 



THE STEAM-ENGINE INDICATOR. I'M 

Draw through e, a line perpendicular to the atmos- 
phere-line. This will' be the clearance-line. 

136. Method of Combining Indicator-cards. — In 
comparing the performance of a compound or multi- 
cylinder engine with that of a simple engine, it is 
sometimes found helpful to combine the cards from 
the different cylinders of the former, plotting them to 
the same scale of pressure and volume. The follow- 
ing method, although open to some criticism, is 
frequently used. The description will apply to the 
case of a compound receiver engine, but may readily 
be modified to suit any combination of cylinders. 

The necessary data are: 

Simultaneous cards from the same end of each 
cylinder. 

Ratio of piston-displacement for the ends from 
which the cards were taken (expressed as a whole 
number). 

Per cent of clearance for each cylinder for the end 
from which cards were taken. 

Scale of spring of cards. 

Barometric pressure. 

Divide the cards into 10 equal spaces by means of 
ordinates drawn perpendicular to the atmosphere-line. 
Measure and record the pressures at both top and 
bottom of the card on each ordinate. 

On a piece of coordinate paper assume ten half- 
inch spaces, as from F to G> Fig. 50, to represent 
the low-pressure piston-displacement. Assume an 
atmosphere-line I-J and construct the low-pressure 
card, using a scale of 20 pounds to the inch. Draw 
the Line of No Pressure, HG, at a distance below the 
atmosphere-line equivalent to the barometric pressure. 



l62 



ENGINEERING LABORATORY PRACTICE, 



At the admission-end of the low-pressure card lay off 
a distance FH to represent the clearance-volume of 
the low-pressure cylinder. At the point //erect the 
Line of No Volume, HK. 



•Cut-off 



% Clearance H.P L.P. 



Piston Displacement H.P L.P. 

Ratio of H.P. to L.P.area= 

Ratio of H.P. to corrected L.P. M.BJP. 

from the original cards= 

Ratio of sum of areas of 

combined cards to area A B C D E A. 




H F G 

Fig. 50. 
From HK lay off KA to represent the high-pressure 
clearance-volume. The scale of volumes should be 
the same as that used for the low-pressure card, viz. : 

L.P. displacement 



1 small division 



100 



THE STEAM-ENGINE INDICATOR. 163 

From A lay off AL equal to the high-pressure dis- 
placement, or equal to 

distance FG -f- cylinder-ratio. 

Now construct the high-pressure card, using the 
same scale of pressure and volume as given above. 

Through the point of cut-off of the high-pressure 
cylinder draw an hyperbola with the lines of no pres- 
sure and no volume as axes. Draw the straight lines 
AB and CD, thus completing the theoretical card 
ABCDEA. 

From the original cards determine the mean effec- 
tive pressure. Multiply the low-pressure M.E.P. by 
the cylinder-ratio. The ratio of the high-pressure 
M.E.P. to the corrected low-pressure M.E.P. stu 
the ratio of the work done by the H.P. and L.P. 
cylinders. It should be equal to the ratio of the 
areas of the combined cards. 

Fill out the items as shown on Fig. 50. The 
original cards, pasted to a blank sheet, should accom- 
pany the report. 

137. Exercise. Calculations from an Indicator- 
card. — The student will be provided with a blank 
form on which are an indicator-card and a list of items 
to be filled out. The first step is to carefully locate 
the events of stroke, cut-off, release, and compression, 
as explained in Section 125. Now measure the 
pressures at the several events and find the per cents 
of stroke (Section 126). Measure the area of the 
card with the planimeter (Section 130, Item 4) and 
determine the clearance (Section 135). The various 
calculations may now be made and entered in the 
proper place. 



164 ENGINEERING LABORATORY PRACTICE. 

In calculating M.E.P., see Section 129; 

Weights of steam, " 133; 

Horse-power, " " 131; 

Reevaporation, M i6i ? 

item 5 ; 

Steam-consumption," 161, 

item 11. 



CHAPTER XII. 
STEAM-ENGINE TESTING. 

138. Classification of Tests. — Tests of the steam- 
engine may be classified as follows: To determine 
whether the valves are correctly set, to measure the 
indicated and brake horse-power, to determine the 
friction of the mechanism, to determine the steam- 
consumption or commercial efficiency, and to investi- 
gate cylinder losses and the interchange of heat 
between the working-fluid and the cylinder-walls. 

139. Valve-setting. — The economical use of steam 
in the steam-engine depends in a large measure upon 
its proper distribution in the cylinder. This requires 
careful setting of the valve or valves and adjustment 
of the valve-gear, which may be accomplished in one of 
two ways: first, by measurements taken directly from 
the valve and valve-seat in different relative positions, 
and second by use of the indicator. Thus the valves 
of Corliss engines and those having a complicated 
valve-gear are generally adjusted by taking a card 
from each end of the cylinder, using a slow speed and 
a light spring in order that the events of the stroke 
may be plainly marked. The valve connections may 
then be changed until the events are correctly placed. 

The method by use of the indicator is the more 
accurate for high-speed engines and when the valves 

165 



l66 ENGINEERING LABORATORY PRACTICE. 

are not easily accessible, rendering actual measure- 
ment difficult. For low-speed engines, the method by 
measurement is to be preferred, as giving more accu- 
rate results. 

140. General Definitions. — The Head End is the 
end of the cylinder farthest from the crank. 

The Crank End is the end of the cylinder nearest 
the crank. 

Steam-lap is the distance in inches which the valve 
moves from its mid-position to its position when the 
admission of steam to the cylinder begins, as shown in 
Fig. 51. The steam-lap is sometimes called outside 
lap, in the case of a valve taking steam on the outside. 

Exhaust-lap is the distance in inches which the 
valve moves from its mid-position to its position 
when the release of steam from the cylinder begins, 
as shown in Fig. 51. In the case of a valve taking 
steam on the outside, the exhaust-lap is sometimes 
called inside lap. It may become equal to zero or 
become negative, in which latter case it is termed 
exhaust or inside clearance. 

Lead is the amount in inches by which the valve 
uncovers the steam-port when the crank is on the 
dead-center. 

The Events of the Stroke, admission, cut-off, release, 
and compression, may each be expressed as the dis- 
tance from the position of the piston when the eveni: 
takes place, to the end of the cylinder at which admis- 
sion occurred or by the fraction representing the per- 
centage of this distance to the full stroke. All head- 
end events should be measured from the head end of 
the cylinder and all crank-end events should be meas- 
ured from the crank end, as shown on Fig. 44. 



STEAM-ENGINE TESTING. 



167 



Equal Cut-off represents the condition when the per 
cent of cut-off for the head end of the cylinder is 
equal to the per cent of cut-off for the crank end. 



Steam Lap 



Steam Lap 




Exhaust Lap 



^•Exhaust Lap 




Fig. 51. 

Equal Lead represents the condition when the 
amount of lead on the head-end center is equal to that 
on the crank-end center. 

141. Specific Directions (for slide-valve engines). 
— To Set for Equal Cut-off, — The valve must first be 
so placed on its stem that its travel will be equal on 



1 68 ENGINEERING LABORATORY PRACTICE. 

both sides of the mid-position. To do this, move the 
engine (or turn the eccentric on the shaft) until the 
valve reaches one extreme point of its travel, and 
measure the amount by which the open port is un- 
covered. Then place the valve at the opposite 
extremity of its travel and take similar measurements 
of the other port. If the measurements do not 
agree, correct by moving the valve on its stem away 
from the port having the least opening, by an amount 
equal to one half of the difference between the meas- 
urements. Repeat the entire operation until correct. 
The motion of the valve is now symmetrical with 
the ports, and it remains to so fix the eccentric on the 
shaft that the motion will bear the required relation 
to the motion of the piston, i.e., will cut off the steam 
on each end of the cylinder after the piston has 
travelled equal distances from the ends of the stroke. 
To do this, place the cross-head at the required per 
cent of stroke at which cut-off is to take place, as 
shown by marks on the guide, and move the eccentric 
on the shaft, turning it in the direction in which the 
engine is to run, until the valve is just cutting off the 
steam from the end of the cylinder from which the 
piston is travelling. Now fasten the eccentric in this 
position and turn the engine over until the piston has 
travelled the same distance in the other direction. If 
the valve is now just cutting off the steam from the 
opposite end of the cylinder, the setting is correct. 
If the valve fails to cut off, or has travelled too far, 
move it upon its stem until one half the error is cor- 
rected and then turn the eccentric on the shaft to 
correct the other half, that is, until the valve just cuts 
off. Now turn the engine to its first position and 



STEAM-ENGINE TESTING. 



169 



note the location of the valve. If not cutting off, 
correct as for the other end. Repeat this process 
until the desired result is obtained. 

After setting the valve to the required performance 
as explained above, fill out the tabular statement on 
the form shown below. The per cent of stroke at 
release and compression can be obtained by reference 
to the valve and valve-seat plan, found in the Common- 
place-book. From the results obtained, construct 
the theoretical indicator-card (Fig. 52), assuming 100 




Cut 



Initial Pressure 100^ 
Back Pressure 5 



Scale of Spring 50*" 
-Adm. Adm. 



xComp. 




Comp. 



Fig. 52. 



pounds initial steam-pressure and five pounds back- 
pressure, using a scale of 50 pounds to the inch and 
making the card four inches long. 

To Set for Equal Lead. — The valve must first be so 
placed on its stem that its travel will be equal on both 
sides of the mid-position, as explained in the first 
paragraph of Section 141. 

Then put the engine on the head-end center and 
move the eccentric on its shaft in the direction which 
the engine is to run, until the head-end port is open 
by the amount of the lead and any further motion of the 
valve in the same direction will open the port wider. 
Fix the eccentric at this point. Turn the engine over 
to the opposite dead-point and note if the lead on 



170 ENGINEERING LABORATORY PRACTICE. 

the crank end is the same. If it is not, divide the 
error into two parts and correct one half by moving 
the valve on its stem and the other half by slipping 
the eccentric. Repeat until correct. 

After setting the valve to the required performance, 
fill out the tabular statement on the form shown 
below. The per cent of stroke at release and com- 
pression can be obtained by reference to the valve and 
valve-seat plan, found in the Commonplace-book. 
From the results obtained, construct the theoretical 
indicator-card (Fig. 52), assuming 100 pounds initial 
steam-pressure and five pounds back-pressure, using a 
scale of 50 pounds to the inch and making the card 
four inches long. 

142. Form for 

VALVE-SETTING. 

Directions: Date 

Mr will set 

valve of engine 

to give ; engine to run 



(Signed) Instructor. 



Report : 

Having complied with the foregoing directions I hav^ohtained 
results which are as follows : 



Per cent of admission. . . . 
11 " cut-off 

11 V " release 

M H " compression .. 
Lead in inches 



Head End. Crank End. 



(Signed) , 

[Attach card (or cards) to this space by pasting at the upper edge only.] 



STEAM-ENGINE TESTING. 171 

143. Valve-setting by Indicator. — In many cases 
it is impossible or inconvenient to set valves by 
measurement on account of their inaccessibility or for 
other reasons. In such cases recourse is had to the 
indicator-card, from which an approximate determina- 
tion of the events of the stroke may be made. Let 
it be required to set the valve of an engine to give 75 
per cent cut-off on each end of the cylinder, the engine 
to run over, and let it be assumed that the valve 
travel has been equalized, i.e., made symmetrical on 
both sides of the mid-position. The process consists 
in taking an indicator-card from each end of the 
cylinder with the engine under a medium load, using 
as light a spring in the indicator as is compatible with 
the steam-pressure. If the cut-off shown by the cards 
is not that desired, make such change in the angular 
advance of the eccentric or the length of the rod as 
will correct the error, and repeat until the desired 
result is obtained. 

Specific Directions. — Read Sections 120 and 148 on 
the use of the indicator and on the care of the engine. 
Having the indicator in place and lubricator and oil- 
cups filled, start the engine and bring slowly up to 
speed and conditions of load desired. After the 
engine has been running a short time, take an indi- 
cator-card for each end and locate cut-off as explained 
in Section 125. 

If it is not at the required per cent of stroke, stop 
the engine and shift the eccentric on the shaft the 
amount deemed necessary to correct the error. Re- 
peat until correct. 

Stop the engine, shut off lubricator and oil-cups, 



172 ENGINEERING LABORATORY PRACTICE. 

remove and clean the indicator, and leave the engine 
in good condition. 

Measure the valve-travel and find the ratio of the 
length of the crank to that of the connecting-rod. 

In the Report state the method of procedure, the 
number of adjustments made, and present the last 
card taken, with all events located and per cents of 
stroke entered at the respective places. Draw on the 
report sheet a Zeuner diagram, assuming the same 
cut-off as that for which the valve was set. The 
valve and seat dimensions may be found in the 
Commonplace-book. Compare the per cents of re- 
lease, compression, and admission shown by the valve- 
diagram and by the indicator-card. 

144. Steam-distribution of Locomotive Link- 
motion. — The Stephenson link-motion is in almost 
universal use in this country for locomotive valve-gears. 
Since the economy of the machine is, in a measure, 
dependent on the steam-distribution, the design of a 
link-motion which will give a suitable distribution at all 
cut-offs is a matter of importance in locomotive design. 

The object of this experiment is to investigate the 
distribution of steam given by a link-motion of pro- 
portions similar to those used in locomotive practice. 
The apparatus consists of a model link-motion, so 
constructed that it can be set to the dimensions of the 
valve-gear of any locomotive in regular service. 

Specific Directions. — The experiment consists in 
placing the reverse-lever in different positions and 
noting the per cents of stroke at which the several 
events occur. The events to be determined are (1) 
admission, (2) cut-off, (3) release, and (4) compression 
for each end of the cylinder and each notch of the 



STEAM-ENGINE TESTING. 



173 



reverse-lever, forward and back. The events are 
determined with reference to the per cent of piston 
travel accomplished when they take place. To this 
end the piston is provided with a scale graduated in 
100 parts. All events for the head end are said to 
take place when the piston is at certain per cents of 
its travel from the head end, whether the piston is 
moving from or to the head end (see Fig. 44). Note 
that when the crank is uppermost and moving toward 
the cylinder the model is " running forward/' 

Commence at the longest cut-off, running forward, 
and proceed with each notch in turn as far as time 
will permit. Be careful to reverse the motion of the 
model when the reverse-lever passes the center notch. 
The Report should correspond to the following form: 

145. Form. 



REPORT ON 



STEAM-DISTRIBUTION OF LOCOMOTIVE 
LINK-MOTION. 



Observers < 



Date 



Head End. 


Crank End. 


Number of 
Notch. 


Adm. 


Cut. 


Rel. 


Comp, 


Adm. 


Cut. 


Rel. 


Comp. 





















146. Indicated Horse-power. — The factors in the 
indicated horse-power of an engine are the size of the 
cylinder, the revolutions per minute, and the mean 



174 ENGINEERING LABORATORY PRACTICE. 

effective pressure on the piston. Its determination 
involves the taking of indicator-cards and simultaneous 
readings of the speed for a sufficient length of time to 
secure observations showing the average performance 
of the engine. From the data thus secured the indi- 
cated power may be calculated. 

Specific Directions, — This test should be conducted 
by two men, one taking indicator-cards and the other 
speed readings. These positions may be interchanged 
half-way through the test. The accessory apparatus 
needed is an indicator, a speed-counter, and a whistle. 
Prepare the blank log-sheet according to the form 
shown below. Before the test it will not be necessary 
to rule up more than the portion headed Running 
Log, leaving space for the other data as shown. 
Before the test read carefully Sections 120 and 148 on 
the use of the indicator and the care of the engine. 
Make the test forty-five minutes in duration, and take 
cards every five minutes. The speed-reading should 
be taken, beginning with the signal for the card and 
continuing for one minute. 

After the test find the dimensions of the engine 
from the Commonplace-book. Calculate the M.E.P. 
from the cards by the method of ordinates as explained 
in Section 128. Find the indicated horse-power as 
explained in Section 131, using the average M.E.P. 
of the cards from each end. 

Under the head of minimum and maximum horse- 
power, enter the horse-power shown by the cards 
having respectively the lowest and highest average 
M.E.P. for the two ends. Make out the report in 
the form shown below and accompany it with an 
average card, pasting the same to the report. 



STEAM-ENGINE TESTING. 

147. Form of 

REPORT ON INDICATED HORSE-POWER 



175 



OF A 



Observers \ 



Date, 



CONSTANTS OF THE ENGINE. 

Dia. of cylinder in. Area of piston, H. E. 

Dia. of piston-rod in. C. E. 

Length of stroke ft. 

RUNNING LOG. 



sq. in. 
sq. in. 



Number. 


Time. 


R. P. M. 


M. E. P. 


Remarks. 


H. E. 


C. E. 














Total 












Average. . . . 













Average I. H. P. Max. I. H. P. Min. I. H. P. 



H. E. 
C. E. 



Total. 

148. Care of the Steam-engine. — The following 
are brief directions for the operation and care of the 
steam-engine. They are applicable in a general way 
to the ordinary types of stationary engines. 

1. Inspect the engine, piping, etc., carefully, to see 
that the plant is in good order. 

2. Fill lubricator with cylinder-oil and oil-cups 



176 ENGINEERING LABORATORY PRACTICE. 

with engine-oil, and adjust the feed to the required 
amount. Oil around where necessary. 

3. If condensing-engine, start air-pump and turn on 
cooling water to condenser. 

4. Open cylinder and pipe-drains. 

5. Start engine slowly and bring gradually up to 
speed. Shut drain-cocks. 

6. Apply the load gradually as desired. 

7. During the run watch lubricator and oil-cups. 
Feel the bearings occasionally. Use only enough 
cooling water to properly condense the steam. 

8. After the run, remove the load gradually, stop 
engine and air-pump. Shut off condenser cooling 
water and stop lubricator and oil-cups. Open drains. 
Clean the plant thoroughly. 

Lubricators. — In Fig. 53 is shown a sectional view 
of a sight-feed lubricator. The top and side connec- 
tions lead to the steam-pipe, the latter at a point 
nearest the engine. Steam enters the upper connec- 
tion, is condensed, and as water flows through the 
small curved pipe to the bottom of the large chamber, 
which is filled with oil. The oil thus displaced enters 
the top of the second small pipe, flows downward by 
the regulating-valve, rises through the glass, which is 
filled with water, and reaches the main steam-pipe 
through the side connection. In filling the lubricator 
it is necessary to shut off the regulating-valve and the 
valve in the upper connection. The oil-chamber may 
then be drained and filled. The left-hand glass serves 
to indicate the level of oil in the chamber. If the 
sight-feed glass becomes clogged with oil, it may be 
cleaned by shutting the feed-regulating valve and 
opening the small valve immediately to the right of 



STEAM-ENGINE TESTING. 



177 



"5enior ,, S.F,Lubricator. 

theLunkenheimerCo. 

Cin,,Ohio. 




FlG. 53. — LUNKENHEIMER LUBRICATOR. 



1 7 8 



ENGINEERING LABORATORY PRACTICE. 



the latter. Steam will then blow through from the 
main steam-pipe and clean the glass. On closing the 
small valve allow the glass to fill with water of con- 
densation before opening the feed-valve. 

In Fig. 54 is shown a lubricator of another make. 
This instrument is fitted with a condensing-bulb A2, 




Fig. 54. — Detroit Lubricator. 
the latter being provided with a valve A4. between it 
and the body of the lubricator. In filling the oil- 
chamber this intermediate valve is closed, thus retain- 
ing the water of condensation in the condensing-bulb. 



STEAM-ENGINE TESTING. 



179 



149. Friction of the Mechanism. — All the power 
developed in the cylinder of the steam-engine re- 
appears at the brake-wheel except that absorbed by 
the friction of the mechanism. The purpose of this 
test is to determine the ratio between this frictional 
horse-power (F.H.P.) and the indicated horse-power 
(I.H.P.). The method consists in taking simultaneous 
observations of the indicated and brake horse-powers 
under the conditions of running for which the friction 
is desired. 

In case it is impossible to fit the engine with 
a brake, the friction of the engine may be found 
when the engine is running light by observing the 
I.H.P. under no load. This, however, does not 
represent the friction when the engine is under load, 
since that quantity varies somewhat under different 
conditions of running. 

Specific Directions. — Run twelve tests, the first to 
be under no load, the twelfth to be under the maxi- 
mum load, and the remainder to be under loads dis- 
tributed between the first and twelfth. The tests 
should be four minutes in duration, witn cards and 
observations every two minutes. The auxiliary 
apparatus needed is an indicator, a speed-counter, 
and a whistle. 

Prepare a Running Log in accordance with the 
following form : 

RUNNING LOG. 



Test No. 



No. of 
Gong-. 



_,. No. of 

Time. Card> 



Steam 
pressure. 



R.P.M 



Brake 
Load. 



M. E.P. 



H. E. 



C. E. 



i8o 



ENGINEERING LABORATORY PRACTICE. 



Before the test read Section 120 on the use of the 
indicator and Section 148 on the care of the engine. 
Start the engine slowly under no load, and after the 
proper conditions are obtained take a few preliminary 
cards before commencing the test. 

The Report should include the Running Log, sample 
cards, a statement of the dimensions and constants of 
the engine, and the calculated results. It should be 
made out in accordance with the form given below. 
The directions for finding M.E.P. are given in Section 
129; for I.H.P. in Section 131 ; for B.H.P. in Section 
68 et seq. 

The formula for mechanical efficiency is 

B.H.P. 
100 X TjOV 

Accompany the report by two curves, one showing 
the relation between F.H.P. and I.H.P. ; the other, 
the relation between mechanical efficiency and I.H.P. 
These should be plotted on a single sheet of plotting- 
paper. 

150. Form of 

REPORT ON FRICTION TEST 

OF 



Observers I 

Dia. of cylinder in. 

Dia. of piston-rod in. 

Length of stroke ft. 

SUMMARY OF RESULTS 



Date. 



Area of piston, H. E sq. in, 

C. E sq. in. 



No. of Test. 



I 
2 
3 
4 
etc. 



Steam- 
pressure. 



R. P. M. 



I.H.P. 



B. H. P. 



F. H. P. 



Mechanical 
Efficiency. 



STEAM-ENGINE TESTING. l8l 

151. Commercial Efficiency. — The commercial effi- 
ciency of the steam-engine is usually expressed as the 
number of pounds of dry steam used per I.H.P. per 
hour, or sometimes per B,H.P. per hour. To deter- 
mine this quantity it is necessary to run the engine 
under the conditions which it is desired to investigate 
and measure the I.H.P. and the water-consumption. 
To this end the engine must be fitted with an accurate 
indicator reducing-motion, and the indicators, prefer- 
ably one for each end of the cylinder, should be placed 
as close to the cylinder as possible to avoid the errors 
due to long connections. An absorption-dynamometer 
should be provided to absorb and measure the work 
done by the engine. The steam-consumption is 
preferably obtained by leading the exhaust-steam to 
a surface condenser, where it may be collected as 
water and weighed. The condenser may or may not 
be fitted with an air-pump. A calorimeter of some 
approved form, such as the throttling calorimeter, 
should be provided to determine the quality of steam 
used (see Section 59). This should be located as close 
to the engine as possible. In case the accessory 
apparatus, such as gages, thermometers, indicator- 
springs, and weighing-barrels, have not previously been 
calibrated, this must be carefully done before the test, 
keeping record of all results. 

Specific Directions. — Observers will be needed for 
the test in accordance with the following schedule: 

1. Log and time ) . , 
ur b , r > in charge. 

2. Weight of steam ) 

3. Indicator, head end. 

4. Indicator, crank end. 

5. Speed and load. 



1 82 ENGINEERING LABORATORY PRACTICE. 

6. Miscellaneous observations. 

Secure the following accessory apparatus: Two in- 
dicators with springs to suit steam-pressure (see Sec- 
tion 119), indicator-cards, one speed-counter, one 
whistle, one 212 F. thermometer, and one 400 F. 
thermometer if a throttling calorimeter is used. 
Prepare the blank Running Log, making provision for 
the following items: 

1. Time. 

2. R.P.M. 

3. Brake load. 

4. Back pull on brake (if any). 

5 . Steam-pressure. 

6. Vacuum (if any). 

7. Barometric pressure. 

8. Pressure in calorimeter. 

9. Temperature in calorimeter. 

10. Temperature of room. 

11. Weight of condensed steam. 

The test should be from one hour to one hour and 
a half long, depending upon the constancy of the 
running conditions. Observations and cards should 
be taken every five minutes. Before the test, read 
Section 120 on the use of the indicator and Section 
148 on the care of the engine. Having the indicators 
in place and observers posted, start the engine and 
secure the desired running conditions. Start the test 
by taking time, cards and observations and commenc- 
ing the weighing of water. 

During the test keep all running conditions" as 
constant as possible. Watch the lubricator and oil- 
cups. Keep only sufficient cooling water on the con- 
denser to prevent the condensed steam from vaporiz- 



STEAM-ENGINE TESTING. 



183 



ing as it emerges. After the test, stop the engine, shut 
off the cooling water from the condenser, stop the lu- 
bricator and oil-cups, remove and clean the indicators, 
collect all logs and cards, and see that the former are 
dated and signed with the initials of the observer. 

Report. — The Report should be accompanied by 
the Running Log or Logs, and all cards taken. It 
should include the following items: 



CONSTANTS OF THE ENGINE. 

Clearance (both ends). 
Kind of brake. 
Brake constants. 
Make of condenser. 
Make and numbers of in 

dicators. 
Scale of spring. 



Type of engine. 
Make of engine. 
Size of cylinder. 
Diameter of piston-rod. 
Area of piston (both ends) 
Piston-displacements. 
Engine constants. 



Duration of test. 

Steam-pressure. 

R.P.M. 

Brake load, net. 

Vacuum. 



OBSERVED DATA. 
Averages. 

Barometer. 

Pressure in calorimeter. 
Temp, in calorimeter. 
Temperature of room. 
Wt. of cond. steam (total) 



CALCULATED DATA. 

Mean effective pressure. H.E. and C.E. (Section 
129). 

Indicated horse-power. H.E. and C.E. (Section 

131)- 

Indicated horse-power, total. 

Brake horse-power (Section 68). 



1 84 ENGINEERING LABORATORY PRACTICE. 

Frictional horse-power (Section 161, item 19). 
F.H.P. in per cent of I.H.P. 
Ratio of B.H.P. to I.H.P. 
Quality of steam (Section 59). 

Pounds of dry steam per I.H.P. per hour, by tank 
(Section 161, item 12). 

* Pounds of dry steam per I.H.P. per hour by in- 
dicator (Section 161, item 11). 

* Clearance from the card (Section 135). 

In case no calorimeter is available, the steam may 
be assumed to be 98 per cent dry if the distance from 
boiler to engine is not great and the steam-pipe is 
well covered. 

152. Investigation of Cylinder Losses. — In more 
extended investigations of steam-engine performance 
than that described in the preceding section, it is cus- 
tomary to make an analysis of the action of the steam 
in the cylinder, with a view to discovering the losses 
occasioned by changes of condition of the steam, inter- 
change of heat between the steam and the cylinder- 
walls and kindred causes. One method of making a 
complete investigation of such losses is known as 
Hirn's Analysis. f Another method is the Entropy 
Temperature Analysis.;}; 

In order to determine the change in condition of 
the steam during different parts of the cycle, the 

* Calculate the weights of steam for this item for a pair of 
sample cards whose combined M.E.P. corresponds most nearly to 
the average for the test. The clearance is found from the same 
cards. 

f See Peabody's "Thermodynamics of the Steam-engine," page 
185. 

X " Entropy Temperature Analysis of Steam-engine Efficiencies," 
by Reeve. 



STEAM-ENGINE TESTING. 1 85 

following items must be added to the " Calculated 
Data ' ' as given in Section 151. 

Absolute pressure at cut-off, head and crank end 
(average of all cards). 

Absolute pressure at release, head and crank end 
(average). 

Absolute pressure at compression, head and crank 
end (average). 

Per cent of stroke at cut-off, head and crank end 
(average). 

Per cent of stroke at release, head and crank end 
(average). 

Per cent of stroke at compression, head and crank 
end (average). 

Weight of steam per revolution at cut-off (Section 
161, item 2). 

Weight of steam per revolution at release (Section 
161, item 3). 

Weight of steam per revolution at compression 
(Section 161, item 4). 

Reevaporation per revolution (Section 161, item 5). 

Reevaporation per I.JH.P. per hour (Section 161, 
item 6). 

Weight of steam per revolution by tank (Section 
161, item 7). 

Weight of mixture in cylinder per revolution, maxi- 
mum (Section 161, item 8). 

Per cent of mixture accounted as steam at cut-off 
(Section 161, item 9). 

Per cent of mixture accounted as steam at release 
(Section 161, item 10). 

In case it is desired to use Hirn's Analysis, the 



186 ENGINEERING LABORATORY PRACTICE. 

following observations will need to be added to the 
Running Log, as given in Section 151 : 

Weight of cooling water. 

Initial temperature of cooling water. 

Final temperature of cooling water. 

Temperature of condensed steam. 

153. Method of Measuring Clearance. — The clear- 
ance of a steam-engine cylinder is all of the clear 
space between the piston and the face of the valve, 
when the piston is at the beginning of its stroke. It 
is usually expressed as a per cent of the piston-dis- 
placement, and should be found for each end of the 
cylinder. The piston-displacement for each end is 
the area of the piston on that end in square feet, 
multiplied by the length of the stroke in feet. 

The method of determining the clearance consists 
in placing the engine on center and filling the clear- 
ance-space with water, noting the weight required to 
fill. Knowing the temperature of the water, the 
volume can then be found. This volume divided by 
the piston-displacement for that end and multiplied 
by 100 will give the per cent of clearance for the 
cylinder end under consideration. 

The process of getting the water into the cylinder 
depends largely upon the construction of the engine. 
It must be poured in at the highest point of the 
cylinder in order to avoid entrapping air in the 
clearance-space. 

For a plain slide-valve engine, with the valve-box 
on the side, it may usually be poured in through the 
indicator-cocks. In such a case it will be necessary to 
disconnect the valve-rod and adjust the valve to cover 
the ports, clamping it in place. A block of wood with 



STEAM-ENGINE TESTING. 1 87 

a rubber gasket may be used instead of the valve. For 
a slide-valve engine with the valve on top it is best to 
remove the valve-box cover and valve, and pour in 
through the port. For a Corliss engine, remove the 
steam-valves and use the ports thus exposed. In 
general an examination of the engine will suggest the 
course to be followed. 

Specific Directions. — Provide two cans of water, a 
and b, weigh each carefully and note the temperature. 
With a fill the clearance-space as rapidly as possible 
and note the time occupied in filling. Then with b 
pour in to replace that lost by leakage, maintaining 
the level for one minute from the time the original 
filling was completed. Weigh both cans and note the 
weight of water used. 

The weight used from can a will represent the 
weight required to fill the clearance-space, subject to 
the following correction: One half the amount used 
from can b, multiplied by the time in minutes occupied 
in the original filling, may be assumed to have leaked 
out during the original filling, and this amount is to be 
subtracted as a correction from the weight used from 
can a. From the corrected weight thus obtained 
and the temperature, the volume may be calculated. 

If the correction to be made is large, the result will 
be only approximately correct. In such a case it 
may be well to attempt to stop the leakage, which is 
usually between the piston and the cylinder, by oiling 
the cylinder thoroughly with a heavy oil. It is often 
thought necessary that the engine be warmed up by 
steam before the clearance is obtained, that working 
conditions may be had, but it is doubtful if such a 
precaution is necessary. 



1 88 ENGINEERING LABORATORY PRACTICE. 

154. Advanced Work in Steam-engine Testing. 

— Effect of Load on Economy. — To determine the 
most economical load for a given speed and steam- 
pressure, run a series of five tests at a constant speed 
and steam-pressure to be assigned by the instructor. 
For the first test let the load be zero. For the fifth 
test, let the load be as large as can be carried under 
the assigned conditions, and let the intermediate tests 
be under intermediate loads. The directions will 
assume that a condenser is employed to measure the 
water-consumption. 

All tests should be of 30 minutes' duration, the 
conditions to be maintained for 15 minutes before the 
test begins, and the test to be conducted and worked 
up in all respects as explained in Section 151. 

The Report should include: 

1. A statement of the purpose of the tests. 

2. A brief description of the plant. 

3. A statement of constant conditions. 

4. A copy of all calibrations, measurements, and 
observed data. 

5. A tabulated statement of calculated results. 

6. Curves showing the following relations: 

{a) Indicated and brake horse-power with per cent 
of cut-off (if an automatic cut-off engine). 

{U) Pounds of steam per I.H.P. per hour with indi- 
cated and B.H.P. 

7. Conclusions as to the most efficient load under 
the conditions. 

8. Sample cards. 

Effect of Different Steam-pressures on Economy. — To 
determine the effect of different steam-pressures on the 
economy of a steam-engine, run a series of five tests 



STEAM-ENGINE TESTING. 1 89 

at constant speed and two-thirds load under steam- 
pressures ranging from 60 to 200 pounds pressure. 

Make all tests 30 minutes in duration, and let the 
conditions be maintained for at least 15 minutes 
before the test is begun. The tests should be con- 
ducted and worked up as described in Section 151. 

The Report should include the following: 

1. A statement of the purpose of the tests. 

2. A brief description of the plant. 

3. A statement of the constant conditions. 

4. A copy of all calibrations, measurements, and 
observed data. 

5. A tabulated statement of calculated data. 

6. Curves showing the following relations: 

(a) Indicated and brake horse-power with steam- 
pressure. 

(b) Steam-consumption with steam-pressure. 

155. Tests of Compound Engines. — The purpose 
of, and methods employed in, compound engine- 
testing are similar to those relating to the simple 
engine. Read the introductory portion of Section 
151. 

Specific Directions. — Observers will be needed for 
the test in accordance with the following schedule: 

1. Log and time ) . , 
m b t r m charge. 

2. Weight of steam ) 

3. Indicators, high-pressure, head and crank. 

4. Indicators, low-pressure, head and crank. 

5. Revolutions, pressures, and miscellaneous obser- 
vations. 

6. Brake load. 

Secure the following accessory apparatus: Four 
indicators with springs to suit steam-pressure (see 



I90 ENGINEERING LABORATORY PRACTICE. 

Section 119), indicator-cards, whistle, thermometers 
for temperature of room, and calorimeter. 

Prepare the blank Running Log to cover the fol- 
lowing items: 

1. Time. 

2. Counter or R.P.M. 

3. Brake load. 

4. Steam-pressure. 

5. Pressure in receiver. 

6. Vacuum. 

7. Barometer. 

8. Pressure in calorimeter. 

9. Temperature in calorimeter. 
10. Temperature of room. 

1 j. Weight of condensed steam. 
Conduct the test as specified in Section 151. The 
Report should cover: 

1. Constants of the engine. 

2. Running logs, averaged. 

3. Tabulated data from cards showing M.E.P. and 
pressures and per cents of stroke at the different 

events (see Section 130). 

4. Calculated data. 

Indicated horse-power, H.P., L.P., and total. 

Brake horse-power. 

Frictional horse-power. 

F.H.P. in percent of I.H.P. 

Ratio of B.H.P. to I.H.P. 

Quality of steam. 

Pounds of dry steam per I.H.P. per hour by tank. 

Number of expansions in H.P.C. 

Number of expansions in L.P.C. 

Total number of expansions, 



STEAM-ENGINE TESTING. I9I 

Ratio of work done in H.P.C. to that in L.P.C. 

Ratio of maximum pressure on H.P. and L.P. 
pistons. 

Initial pressures, H.P.C. and L.P.C. 

Final pressures, H.P.C. and L.P.C. 

Drop in pressure, H.P. final to L.P. initial. 

Weight of steam at cut-off, H.P.C. per revolu- 
tion. 

Weight of steam at release, H.P.C. per revolu- 
tion. 

Weight of steam at cut-off, L.P.C. per revolu- 
tion. 

Weight of steam at release, L.P.C. per revolu- 
tion. 

Reevaporation during expansion, H.P.C. 

Reevaporation during expansion, L.P.C. 

Condensation (or reevaporation) between cut-off 
H.P.C. and cut-off L.P.C. 

5. Present a representative set of cards. 

6. Take head-end cards from same set (item 5) and 

plot to same scale of pressures and volumes 
(see Section 136). 

156. Directions for Equalizing the Work of a 
Compound Engine. — The work done by the cylinders 
of a compound engine should be equally distributed 
between the two cylinders. This condition will be 
realized when the mean effective pressures are in- 
versely proportional to the areas of the cylinders, 
the length of stroke being the same. 

The method of equalizing the work is as follows: 
Take simultaneous cards from both cylinders and 
determine the average M.E.P. If the ratio between 
them is not inversely proportional to the cylinder 



192 



ENGINEERING LABORATORY PRACTICE. 



areas, and it is found, for instance, that the M.E.P. 
of the L.P. cylinder is too small, shorten the cut-off 
on the L.P. cylinder. This will increase the back- 
pressure on the H.P. cylinder and increase the initial 
pressure of the L.P. cylinder. Take another set of 
cards, and if not correct, repeat the process. 
In reporting results give: 

1. A statement of the result to be accomplished. 

2. A tabulated statement as below: 





M. E. P.— H. P. C. 


M. E. P.-L. P. C. 


Ratio of 

M.E.P. in 

H. P. C. 




H. E. 


C. E. 


Ave. 


H. E 


C. E. 


Ave. 


to that in 
L. P. C. 


Eng. as found. 

ist change.. . . 

2d change. . . . 

Etc. 

















3. A statement of the maximum piston-pressures 
after equalization. 

157. Locomotive Testing. — Tests of locomotives 
are of two general kinds, those made on the road 
under conditions of actual service and those made on 
specially devised testing plants, where the engine 
may be placed under conditions similar to those mQt 
with in road service. For all tests involving an 
accurate determination of the engine and boiler per- 
formance the shop test is to be preferred, since by 
that method all conditions may be maintained with 
great constancy, a feature impossible with road tests. 

The method of conducting the tests on the road 
varies according to the purpose for which the test is 
made, but for all ordinary road tests the following 
method, recommended by the American Society of 



STEAM-ENGINE TESTING. I93 

Mechanical Engineers,* is standard. The code pro- 
vides for both road and shop tests. 

158. A. S. M. E. Standard Method of Testing 
Locomotives. 

I. Preparations for Test, and Location of 
Instruments. f 

A. The locomotive should be put in good condition 
preparatory to the test. The boiler and tubes should 
be tight, and both the interior and exterior surfaces 
should be clean, and if possible free from scale. 
There should be no lost motion in the valve-gear, 
and the valves should be set properly. No change 
in the engines should be allowed during the progress 
of a series of tests, unless so ordered for the pur- 
poses of the trial. 

A glass water-gage should be fitted to the boiler, if 
not already provided. A rod should be attached to 
the reversing-lever and carried forward to the front 
end of the boiler, where a graduated scale is provided 
and suitably marked, so that the position of the 
reversing-lever can be seen at a glance by the person 
taking indicator-diagrams. The throttle-valve lever 
should be provided with a scale to show the degree 
of opening of the throttle. 

B. The valves and pistons should be tested for 
leakage with the engine at rest. The steam-valve 
can be tried by setting the engine so that the valve on 
one side will be at the center of its throw, in which 

* Transactions of the American Society of Mechanical En- 
gineers, vol. xiv, p. 1312. 

f The directions here given apply largely to both shop and road 
tests, but especially to the latter. 



194 ENGINEERING LABORATORY PRACTICE, 

position both ports are usually covered, and pulling 
open the throttle-valve, blocking the drivers if there 
is a tendency for the engine to be set in motion. 
Leakage of the valve, if any occurs, will show itself 
by escaping at the smoke-stack, or at the open drain- 
cocks. The tightness of the piston may be tested by 
setting the engine so that it takes steam, blocking the 
drivers, and opening the throttle-valve. This should 
be tried first on one cylinder anJ then on the other, 
and if desired, it may be tried with the pistons at 
various points in the stroke. The leakage, if any 
occurs, will be shown either at the top of the smoke- 
stack or at the open drain-cock. 

C. The following instruments should be verified or 
calibrated: Steam-gages, draught-gage, pyrometer, 
thermometers for calorimeter and feed-water, water- 
meter, tank, revolution-counter, indicator-springs, 
dynamometer-springs, and dynamometer recording 
mechanism. The radiation loss on the steam-calo- 
rimeter should be determined or the normal readings 
ascertained;* and the quantity of steam which passes 
through the instrument in a given time should be 
measured. 

D. The quantities of steam consumed by the air- 
pump, the blower, and the whistle, under conditions 
of common use, should be determined, thereby 
obtaining data by which to correct for the steam thus 
used. This can best be determined for each one by 
observing the fall of water in the gage-glass when no 
steam is drawn from the boiler for any other purpose, 
the quantity being computed from the data thus 

* Transactions A. S. M. E., vol. xi, p. 793. 



STEAM-ENGINE TESTING. 195 

found, and the dimensions of the boiler. The leakage 
of the boiler should also be found, using the same 
method. 

E. To facilitate the measurement of coal and the 
determination of the quantity used during any desired 
period of the run, it is desirable to provide a sufficient 
number of sacks of a size holding a weight of, say, 
100 pounds, and weigh the coal into these sacks pre- 
paratory to starting on the test. If desired, the sacks 
may be numbered, to facilitate the accuracy of record. 

F. The instruments and other apparatus that should 
be provided, and their locations, are as follows: 

To facilitate the work of operating the indicators 
and reading the instruments at the front end, the 
smoke-box should be surrounded with a wooden 
fence, or" pilot-box, " as it may be called, resting on 
the top of the cow-catcher and extending back far 
enough to enclose also the sides of the cylinders. 
This box is floored over, and the enclosure thus pro- 
vided forms a convenient place for the accommodation 
of the assistants at this end of the locomotive, and it 
affords them some measure of protection against wind 
and rain, as also the jolting and vibrations due to rapid 
travel. 

A special steam-gage with a long siphon is to be 
used for registering the boiler-pressure. It can best 
be located on the left-hand side of the cab. 

The indicator apparatus which is most suitable con- 
sists of a three-way cock for the attachment of the 
indicators, and some form of pantograph motion for 
the driving-rig. The pipes leading from the cock to 
the cylinder should be three-fourths inch diameter 
inside, and they should connect into the side of the 



I96 ENGINEERING LABORATORY PRACTICE,, 

cylinder rather than into the two heads. The indi- 
cator should also be piped so that a steam chest 
diagram can be drawn by it. Sharp bends in the pipe 
should be avoided, and they should be well covered, 
to intercept radiation. The three-way cock should 
be provided with a clamp rigidly secured to the 
cylinder, and thus overcome any tendency of the 
indicators to move longitudinally with reference to 
the driving-rig. Absolute rigidity is highly essential 
in this particular. In both of these the reduced 
motion is transmitted to the indicator through a light 
rod, working horizontally. By this means a cord 
eight or ten inches in length is sufficient for connec- 
tion to the indicator. Care should be taken to set the 
instrument in such a position that the cord-pin in the 
end of the rod travels in a direction pointing to the 
groove in the paper drum. Pantograph motions 
arranged as noted are preferable to the common 
pendulum and quadrant reducing mechanism, with its 
long stretch of cord. 

A draught-gage consisting of a U tube containing 
water, properly graduated in inches, should be con- 
nected to the smoke-box and attached to the side of 
the pilot-box. 

A pyrometer for showing the temperature of the 
escaping gases should be used in a position below the 
tip of the exhaust-nozzles. 

The calorimeter should be attached either to the 
steam-dome at a point close to the throttle-opening, 
or to the steam-passage in the saddle-casting on one 
side, according as it is desired to obtain the character 
of the steam at one point or the other. The former 
location is preferred by the committee. A perforated 



STEAM-ENGINE TESTING. I97 

half-inch pipe should be used for sampling and con- 
veying the steam to the calorimeter-pipe. For 
descriptions of various forms of calorimeters which are 
adapted to locomotive use, see Trans. A. S. M. E., 
vol. X. p. 327, vol. XI. p. 790, vol. XII. p. 825. 

The water-meter should be attached to the suction- 
pipe of the injector, and located at a point where it 
can be conveniently read when the locomotive is 
running. It should be provided with a check-valve 
to prevent hot water from flowing back through it 
from the injector, and a strainer to intercept foreign 
material. 

To measure the depth of the water in the tank, a 
metallic float should be used, carrying a vertical tube 
which slides upon a graduated rod, the lower end of 
which rests upon the bottom of the tank. This 
should be placed at the center of gravity of the 
water-space. If the desired location cannot be used, 
provision should be made for ascertaining the level or 
inclination of the tank. The best device for this pur- 
pose is a plumb-line of a certain known length, pro- 
vided at the bottom with a double horizontal scale, 
having one set of divisions parallel to the side of the 
tank and the other set at right angles to it. From 
the readings on these scales referred to the length of 
the line the level of the tank in both directions can 
be ascertained. A similar device should be attached 
to the boiler to correct for the variation in its inclina- 
tion. The plumb-line may be conveniently attached 
for this purpose at some point near the front end. 

The revolution-counter should be placed near the 
front end of the engine in plain view from the pilot- 
box. It is operated through a belt from the driver 
shaft. This recommendation applies to that form of 



I98 ENGINEERING LABORATORY PRACTICE. 

counter which shows at a glance the exact speed in 
revolutions per minute. 

A stroke-counter should be provided for showing 
the number of strokes made by the air-pump. 

Electric connection should be made between the 
dynamometer-car and the pilot-box, so that dynamom- 
eter records and indicator-diagrams may be taken 
simultaneously. Another provision is a speaking-tube 
leading from the dynamometer-car to the locomotive- 
cab, and one also to the pilot-box. 

G. It is needless, except for a complete record of 
directions for preparatory work, to call attention to 
the desirability of having the test, especially the road 
test, made under the supervision of a competent 
person, who is not only familiar with the details of 
testing, but also with the proper method of firing and 
mechanical operation of the locomotive. This is a 
most important factor, for it is only the clear-headed 
and able experimenter who is likely to obtain satis- 
factory work in this most difficult department of 
engineering tests. 

In the matter of assistants, the conductor of the 
test is best able to judge as to the number required, 
the various duties of the different men, and the 
manner of taking records. A good test can be made 
with eight (8) assistants, distributed in the manner 
indicated in the following list, which gives their 
duties: 

Two (2) cab assistants, who note the reading of the 
steam-gage and the water-meter, the position of the 
throttle-valve and reversing-lever, the height of water 
in the tank, the height of water in the glass water-gage, 
the level of the tank, the number of times the whistle 
is blown, the length of time the safety-valve blows, 



STEAM-ENGINE TESTING. I99 

the length of time the blower is in action, the reading 
of the air-pump counter, the temperature of the feed- 
water in the tank, the time of starting and stopping 
the injector, the time of opening and closing the 
throttle-valve, and the number of sacks of coal used. 
These two observers have previously checked the 
weights of coal placed in the sacks. 

Three (3) pilot-box assistants, one of whom reads 
the pyrometer, the draught-gage, the steam-chest 
gage, the revolution-counter, and marks on the indi- 
cator-diagrams the time, position of reversing-lever, 
steam-chest pressure, and revolutions per minute. 
He also takes the levels of the boiler at stopping- 
places. The other two observers are stationed at the 
cylinders and manipulate the indicators, one being 
employed on each side. 

One (1) calorimeter assistant, who reads the calo- 
rimeter thermometers, and the gages connected with 
the instrument, if these are employed. 

Two (2) dynamometer-car assistants, who record 
time of each start and stop, time of passing each 
station and each mile-post, time of taking each 
indicator-diagram as obtained from signals of the 
indicator men ; and all these readings are marked so 
far as possible on the dynamometer-paper. One of 
these men also assists the cab observer in reading the 
tank-depth and its levels at stopping-places. These 
men also keep a record of the direction and force of 
the wind, and the temperature of the atmosphere. 

An additional assistant is required if the gases are 
sampled and analyzed. 

H. It is of paramount importance, after the com- 
plete preparatory work has been accomplished, that 
the locomotive be subjected to a preliminary run, of 



200 ENGINEERING LABORATORY PRACTICE. 

sufficient duration to make a fair trial of the testing 
apparatus, and to give the various assistants an oppor- 
tunity to become trained in their duties. 

II. Shop Test. 
A . Preparation and Location of Instruments. 
In preparing for a shop test the preparations 
described in Section I should be followed so far as the 
nature of the test requires. When run as a stationary 
engine the locomotive is not circumscribed by the 
conditions of road service, and many provisions re- 
quired on the road are unnecessary. It is unnecessary 
to determine the quantity of steam consumed by the 
whistle and air-pump, for these are not brought into 
use on the shop test ; and no occasion exists for finding 
the quantity lost at the safety-valve, for on the con- 
tinuous shop run the steam-pressure can be maintained 
at a uniform point, and blowing-off readily prevented. 
It is unnecessary to use sacks for the convenient 
measure of coal, because the coal can be readily 
weighed up in lots as fast as needed for the test. It 
is unnecessary to provide a 4< pilot-box," and no fixed 
location of the instruments is required, as on the road 
test. The feed-water may be weighed before it is 
supplied to the tank, and the tank may be used in this 
case as a reservoir, the float showing its depth. The 
meter would thus be unnecessary as the principal 
instrument of measurement, but a meter is in all cases 
useful as a check upon this most important element 
in the data. The long indicator-pipes required on 
the road test may be dispensed with, and one indi- 
cator applied close to each end of the cylinder, a 
practice much to be preferred to the use of a three- 
way cock and the single indicator. The dynamom- 



STEAM-ENGINE TESTING. 201 

eter-car is not required, but its equivalent should be 
provided, consisting of a dynamometer which registers 
the pull on the draw-bar, in the same manner as the 
device used on the road. 

The number of assistants required on a shop test is 
less than that needed for a road test. A good test 
can be made with four (4) assistants distributed as 
follows: 

One (1) assistant for operating indicators. 

One (1) assistant for measuring water. 

Two (2) assistants for general observations and coal 
measurement. 

If the gases are sampled and analyzed, one more 
assistant is required. 

B. Conditions of Test. 

The test should be continued for a run of at least 
two (2) hours from the time normal conditions have 
been established. 

At the close of the test the water height in the 
boiler and the height of water in the tank should be 
the same as at the beginning, or proper corrections 
made for any differences which may exist. 

The fire-box and ash-pit are then cleaned, and such 
unburnt coal as may be contained in the refuse is 
separated, weighed, and deducted from the total 
weight of coal fired. The balance of the refuse is 
weighed, as also the cinders removed from the smoke- 
box. 

During the progress of the test samples of the 
various charges of coal should be obtained, and at its 
close a final sample of these should be selected, dried, 
and subjected to chemical analysis and calorimeter 
test. The weight of the sample is taken before and 



202 



ENGINEERING LABORATORY PRACTICE. 



after drying, to ascertain the amount of moisture 
contained in the fuel. 

C. The Data and Results. 
The data and results of the shop test can best be 
arranged in the manner indicated in Table No. I. 

Table No. 1. 

DATA AND RESULTS OF SHOP TEST ON 

ENGINE, MADE 189 

GENERAL DIMENSIONS, ETC., 

To be accompanied by a complete description, with drawings and 

full dimensions. 

1. Kind of engine 

2. Size and clearance of cylinders 

3. Area of heating-surface 

4. Area of grate-surface 

5. Diameter of exhaust-nozzles 



TOTAL QUANTITIES. 



6. Duration 

7. Weight of dry coal burned, including 0.4J 

weight of wood 

8. Weight of water evaporated corrected for 

moisture in the steam 

9. Weight of ashes and refuse from ash-pan. 

10. Weight of cinders from smoke-box 

11. Percentage of ash, as found by calorim- 

eter test I per cent. 

12. Total heat of combustion per lb. coal as 

found by calorimeter test B. T. U. 

POWER DATA. 

13. Mean effective pressure, high-pressure 

cylinders 

14. Mean effective pressure, low-pressure 

cylinders 

15. Average revolutions per minute 

16. Indicated horse-power, high pressure 

cylinders 

17. Indicated horse-power, low-pressure 

cylinders 

18. Indicated horse-power, whole engine. .. . 

19. Pull on draw-bar 

20. Dynamometer horse-power 



Whole 
Run. 



STEAM-ENGINE TESTING. 
Table No. 1 — Continued. 



203 



21. 


AVERAGES OF OBSERVATIONS. 

Average boiler-pressure 


lbs. 
lbs. 
deg. 
in. 
deg. 
deg. 

per cent. 

per cent. 

lbs. 

lbs. 

lbs. 
lbs. 

lbs. 

lbs. 

lbs. 
lbs. 
lbs. 

lbs. 

lbs. 
lbs. 
lbs. 


Whole 
Run. 


22. 


Average steam-chest pressure 




23. 
24. 

25. 
26. 
27. 


Average temperature of smoke-box 

Average draught-suction 




Average temperature of feed-water 

Average temperature of atmosphere 

Average percentage of moisture in the 
steam 




28. 


Maximum percentage of moisture in the 
steam 




29. 
30. 


HOURLY QUANTITIES. 

Weight of dry coal burned per hour 

Weight of dry coal burned per hour per 
sq. ft. of grate-surface 




31. 


Weight of coal burned per hour per sq. ft. 
of heating-surface 




32. 
33- 


Weight of water evaporated per hour. . . . 

Equivalent weight of water evaporated 
per hour with feeding- water at 100 
and pressure at 70 lbs 




34- 


Equivalent weight of water from 100 at 
70 lbs. evaporated per sq. ft. of heating- 
snrfflrp 




PRINCIPAL RESULTS, COMPLETE ENGINE AND 
BOILER. 

35. Coal consumed per I.H.P. per hour 

36. Coal consumed per dynamometer horse- 

nnwer ner hour 




37. 

38. 


Weight of "standard coal" consumed 
per I.H.P. per hour 

Weight of "standard coal" consumed 
per dynamometer horse-power per 
hour 




39- 
40. 


BOILER RESULTS. 

Water evaporated per lb. of coal 

Equivalent evaporation per lb. of coal 
from and at 21 2° 




41. 


Equivalent evaporation per lb. of com- 
bustible from and at 212 











204 



ENGINEERING LABORATORY PRACTICE. 



Table No. 1 — Continued. 

CYLINDER DATA. 

42. Mean initial pressure above atmosphere. . . 



43- 
44. 
45. 

46. 

47- 

48. 

49- 



lbs. 



Cut-off pressure above zero 

Release pressure above zero 

Compression pressure above zero., 

Lowest back-pressure above or be- 
low atmosphere 

Proportion of forward stroke com- 
pleted at cut-off 

Proportion of forward stroke com- 
pleted at release 

Proportion of return stroke uncom 
pleted at compression 



lbs. 
lbs. 
lbs. 

lbs. 

lbs. 

lbs. 

lbs. 



H.P. Cyl. 



L.P. Cyl. 



CYLINDER RESULTS. 



5L 



52. 



Total water consumed per indicated horse power per hour 
corrected for moisture in steam lbs. 

Water consumed per I. H.P. per hour by cylinders alone 
(from line 51, less all measured losses) lbs. 



55. 



56 



53. Steam accounted for by indicators 

at cut-off 

54. Steam accounted for by indicators 

at release 

Proportion of feed-water used by 
cylinders (line 52) accounted for 
at cut-off 

Proportion of feed-water used by 
cylinders accounted for at re- 
lease 



lbs. 
lbs. 

lbs. 

lbs. 



H.P. Cyl. 



L.P. Cyl. 



So far as these are in common with the data and 
results obtained on the road test, the forms used on 
both kinds of test are identical. 

Reports should give copy of a set of sample indi- 
cator-diagrams, also combined diagram (in case of 
multi-expansion engine), and a chart showing graphi- 
cally the principal data. 



STEAM-ENGINE TESTING. 205 

III. The Road Test. 
A . Preparation and Location of Instruments. 

The preparations required for the road test, and 
the proper location of instruments for the purpose, 
are fully described in Section I, and repetition is 
unnecessary. 

B. The Dynamometer-car . 

With a suitable dynamometer-car the force required 
to move the train, or the pull upon the draw-bar, is 
registered upon a strip of paper travelling at a definite 
rate per mile. The scale upon which this diagram is 
drawn should be as large as is possible within reason- 
able limits; a scale of \ inch per iooo pounds pull 
being suitable, as the maximum registered pull rarely 
exceeds 30,000 pounds. The height of the diagram 
should be measured from a base-line drawn upon the 
paper by a stationary pen, so located that when no 
force is exerted upon the draw-bar the base-line should 
coincide with zero pull. 

The apparatus should be arranged to make a record 
of time-marks in connection with the curve showing 
the pull. A chronometer should be provided, having 
an electric circuit-breaker, by means of which a mark 
is made on the dynamometer-paper every five (5) 
secunds. A better apparatus may be used in which 
a continuous speed-curve is traced upon the paper 
parallel to the curve of pull. The ordinates of this 
curve, measured from a base-line, give the speeds 
desired. 

The location of mile-posts and other points along 
the route should be fixed upon the dynamometer- 
paper by employing an additional pen, and operating 



206 ENGINEERING LABORATORY PRACTICE. 

it by means of electric press-buttons, which are placed 
at convenient points in the car. 

As already noted, a similar device should be pro- 
vided for marking upon the dynamometer-paper the 
time of taking indicator-diagrams. 

The rate of travel of the paper per mile should be 
such that one inch measured upon the diagrams repre- 
sents ioo feet for short-distance work, and for long- 
distance work % inch or J inch should be used to 
represent ioo feet of track. The driving mechanism 
for the paper should be so arranged that it can be 
changed to give these proportions. It is necessary to 
have all the registering-pens located upon the same 
transverse line at a right angle with the direction of 
the movement of the paper, in order that simultane- 
ous data may be recorded. 

C. Method of Conducting the Road Test, 

The locomotive having been brought to the train, 
the steam-pressure being at or near the working- 
point, the fire being clean and in good condition, 
though not over 4 to 6 inches thick, the ash-pan being 
also clean, observations are taken, say five (5) minutes 
before starting-time, of the thickness and condition of 
the fire, the height of water in the boiler, the depth 
in the tank, the levels, the water-meter, and the air- 
pump counter; and thereafter the regular observations 
are carried forward, and coal is fired from the weighed 
sacks. 

Indicator-diagrams should be taken as frequently 
as possible, the intervals between them not being 
over two minutes. 

Other regular observations should be taken at close 



STEAM-ENGINE TESTING. 207 

intervals. Calorimeter readings, when taken, should 
be continued for at least five (5) minutes at one- 
minute intervals. 

At water stations careful records should be obtained 
of water heights and levels of boiler and tank. 

As the end of the route is approached, the fire 
should be burned down so as to leave the same 
amount and the same condition as at the start. When 
the end is finally reached, the fire should be raked, 
and its condition carefully noted. If it differs from 
that which obtained at the beginning, an estimated 
allowance must be made for such difference. 

At the close of the test the height of water in the 
boiler should be the same as at the beginning, or if 
not, the difference, corrected for inclination of the 
boiler, should be allowed for. 

During the process of weighing the coal into sacks 
numerous samples should be obtained, and a final 
sample cf these selected. This is to be dried and 
subjected to chemical analysis and calorimeter test. 
The sample is weighed before and after drying, and 
data obtained for determining the weight of dry coal 
used during the test. 

The duration of the road test is the length of time 
which the throttle- valve is open. 

D. The Data and Results. 

The data and results of the road test may be 
tabulated in a form corresponding in general with that 
recommended for the shop test; viz., Table No. 1. 

159. Locomotive-testing Plants. — The first plant 
for testing locomotives * was established at Purdue 

*A second locomotive-testing plant has been built by the 



208 ENGINEERING LABORATORY PRACTICE. 

University in 1891. The plant was designed by Prof. 
W. F. M. Goss, and consists, in its elements, of a 
locomotive, mounted on supporting wheels (see Fron- 
tispiece) in such a way that it can be run under its 
own steam at speeds equal to those attained in actual 
service and under loads commensurate with its capac- 
ity. The load is supplied by four hydraulic friction- 
brakes of a type devised by Professor Geo. I. Alden, 
which are keyed on to the shafts of the supporting 
wheels and interpose a resistance to their motion. 
Work is thus furnished the locomotive, not in putting 
a section of track behind it, but in moving the top 
of the supporting wheels backward, a condition pre- 
cisely similar in its effect to the load furnished by a 
train on the road. The maximum capacity of the 
four brakes is 800 horse-power. 

The first effect of the retarding action of the brakes 
to the motion of the supporting wheels is the ten- 
dency of the locomotive to move forward with a force 
proportional to the retarding action. This forward 
tendency is opposed by the draw-bar which alone 
holds the locomotive on the supporting wheels and 
which is attached to an Emery dynamometer of 
30,000 pounds capacity, made by Wm. Sellers & Co. 
(Fig. 27), which serves to measure the draw-bar pull. 
Thus the load, and consequently the speed, are very 
readily controlled by varying the amount of water 
flowing to the brakes. 

The locomotive is fired with coal in the usual way, 
and is operated from the cab in a manner precisely 
similar to that employed on the road. 

Chicago and Northwestern Railway at their Chicago shops. The 
general arrangement is similar to that employed in the Purdue 
plant. 



STEAM-ENGINE TESTING. 209 

The plant as originally built was destroyed by fire 
on January 23, 1894. It was immediately rebuilt in 
a new location with many added improvements, 
among which may be mentioned the provision for test- 
ing any locomotive built, up to eight wheels coupled. 
The locomotive originally purchased for use on the 
plant was sold to the Michigan Central Railway in 
June, 1897, and a new machine, known as Schenectady 
No. 2, was purchased in its stead. The following are 
its principal dimensions: 

GENERAL DIMENSIONS. 

Gage 4 '8J".. 

Fuel Bituminous coal. 

Weight in working order 107,200 lbs. 

Weight on drivers 65,700 lbs. 

Wheel-base, driving 8' 6". 

Wheel-base, total 23' 6". 

CYLINDERS. 

Diameter of cylinders — simple 16"; compound, 16" and 30", 

Stroke of piston 24". 

Diameter of piston-rods 2}". 

Size of steam-ports 18" X if". 

Size of exhaust-ports 18" X 3". 

Size of bridges if". 

VALVES. 

Kind Allen-Richardson. 

Maximum travel . 6". 

Outside lap i|". 

Inside lap Line and line. 

WHEELS AND JOURNALS. 

Diameter of drivers, outside tires.. . . 69". 
Diameter and length of driving-jour- 
nal 7i"X8i". 

BOILER. 

Style Extended wagon-top. 

Outside diameter of first ring 52". 

Working pressure 250 lbs. 

Thickness of plates f", f", 9/16", and |". 

Grate-surface . 17 sq. ft. 

Heating-surface 1322 sq. ft. 



2IO ENGINEERING LABORATORY PRACTICE. 

160. Method of Testing. — The method of testing 
employed at Purdue is briefly as follows: The test on 
the boiler is conducted according to the alternate 
method prescribed by the A. S. M. E. The duration 
of the test is, except for very slow speeds, sufficient 
to give a total run of ioo miles. The water supplied 
the injectors is measured in carefully-calibrated 
barrels. The coal is weighed out to the fireman as 
needed. Two indicator-cards are taken on each 
cylinder and one on the right steam-chest. The cord- 
connections are short and the reducing-motion accu- 
rate. The draw-bar pull is measured by an Emery 
hydraulic dynamometer. The speed is measured by 
a revolution-counter and checked by a Boyer speed- 
recorder. The boiler and dry-pipe pressures are regis- 
tered by carefully-calibrated gages, the former being 
checked by a Bristol recording-gage. The draught is 
measured by draught-gages and checked by a Bristol 
gage. A Bristol gage is also employed to record the 
exhaust-pressure. The quality of the steam is deter- 
mined by a throttling-calorimeter on the dome, made 
in accordance with the recommendations of the Com- 
mittee on Locomotive Testing of the A. S. M. E. 

The temperature of the smoke-box gases is deter- 
mined by two methods, the first making use of a Le 
Chatelier pyrometer, and the second employing the 
copper-ball calorimeter described in Section 56. A 
special device is employed to measure the amount of 
cinders thrown out of the stack. 

Observers. — The plant is manned by a force con- 
sisting of one supervisor, one fireman, one assistant 
fireman, two brake-tenders, and observers to the num- 
ber of ten. The duties of the latter are as follows: 



STEAM-ENGINE TESTING. 211 

a. Log and time. 

b. Right-head indicator, Boyer recorder, Bristol 
gages, barometer and temperature of room. 

c. Right-crank indicator and dry-pipe pressure. 

d. Left-head indicator and draft. 

e. Left-crank indicator, steam-pressure, and calo- 
rimeter. 

/. Steam-chest indicator, counter, and brake-pres- 
sures. 

g. Weight and temperature of feed-water. 

h. Weight of coal. 

i. Dynamometer. 

j. Temperature of waste gases and weight of stack- 
cinders. 

The following are the observations taken during the 
test : 

Time. 

Counter. 

Dynamometer. 

Brake-pressures. 

Boiler-pressure. 

Dry-pipe pressure. 

Barometer. 

Pressure in calorimeter. 

Temperature in calorimeter. 

Temperature of room. 

Temperature of waste gases by calorimeter. 

Temperature of waste gases by pyrometer. 

Draft, gross. 

Draft, net. 

Weight of water delivered to injectors. 

Overflow loss from injectors. 

Temperature of feed. 



212 ENGINEERING LABORATORY PRACTICE. 

Height of water in boiler. 

Minutes injectors were in action. 

Loss of steam by calorimeter. 

Position of engine on supporting wheels. 

Weight of coal fired. 

Weight of stack-cinders. 

During the test samples of waste gases and coal are 
taken for analysis. After the test the weight of 
cinders in the smoke-box and of the ash is found and 
a determination of surface-moisture in the coal is 
made. (See Sec. in.) 

161. Method of Working Up Locomotive Tests. 
— The method of working up herein described includes 
those items usually found in the report of an engine 
and boiler test, with the addition of certain others 
relating only to the locomotive. The data from the 
tests are preserved in the form of indicator-cards and 
running logs, accompanied usually by samples of the 
coal, ash, cinders, and smoke-box gases. Analyses 
of the samples are made according to the purpose for 
which the test was run. The results of the analyses 
are not included in the following calculations. 

The Running, Water, and Coal Logs should first be 
averaged and all necessary corrections, such as those 
due to errors of gages, etc., applied. In averaging 
the columns carry the average to two places of deci- 
mals. Then transfer the results to the Summary- 
sheet. 

The cards, except those from the steam-chest, 
should be treated as explained in Section 130. After 
the factors are determined and marked on the cards, 
transfer them to the Card Log. Add and average the 
columns and enter the results in pencil. In averaging 



STEAM-ENGINE TESTING. 21 3 

columns carry the average to two places of decimals, 
except on the Per-cent Log, where they should be car- 
ried to three places of decimals. This should be 
checked. Then transfer to the Summary-sheet. 

Fill in all items on the several logs before commenc- 
ing calculation on the Summary-sheet. 

In calculating volumes at the several events of 
stroke use the piston-displacements as given in the 
4< Commonplace-book " to four places of decimals and 
express the volumes to four places. 

In using the steam tables'* carry all interpolations 
to the number of decimal places given in the table. 

In calculating weights of steam, carry the result to 
four places of decimals. 

In calculating horse-power use the H.P. constant 
to five places of decimals and carry the result to two 
places. 

The calculated results appearing on the Summary- 
sheet are derived as follows: 

1. Indicated horse-pozver is the product of the 
R.P.M., the indicated horse-power constant, and the 
M.E.P., the last two being for the cylinder-end in 
question. The total I. H.P. is the sum of the I. H.P. 
for the four ends. 

2. Weight of steam per revolution at cut-off is the 
sum of the weights (per stroke) for each end at cut- 
off. The weight for one end is found by multiplying 
the weight of a cubic foot of steam at the absolute 
pressure of cut-off by the product of the piston-dis- 
placement for that end in cubic feet into the sum of 
the per cent of cut-off plus the clearance on that 
end. (See Sec. 133). 

* See Peabody's " Tables of Saturated Steam." 



214 ENGINEERING LABORATORY PRACTICE. 

3. Weight of steam per revolution at release is the 
sum of the weights for each end at release. 

4. Weight of steam per revolution at compression is 
the sum of the weights for each end at compression. 

5. Reevaporation per revolution is the difference 
between the weight of steam per revolution at release 
(3) and the weight of steam per revolution at cut- 
off (2). In case the reevaporation is negative, change 
the item to read " Condensation/ ' 

6. Reevaporation per horse-power per hour is the 
product of the reevaporation per revolution (5) and 
the average revolutions per hour, divided by the total 
horse-power. 

7. Weight of steam per revolution by tank is the 
quotient of the total weight of steam used by the 
engine by the total number of revolutions for the test. 

8. Weight of mixture in cylinder per revolution is 
the sum of the weight of steam per revolution by tank 
(7) and the weight of steam per revolution at com- 
pression (4). 

9. Per cent of mixture accounted as steam at cut-off 
is one hundred times the weight of steam per revolu- 
tion at cut-off (2) divided by the weight of mixture in 
cylinder per revolution (8). 

10. Per cent of mixture accounted as steam at release 
is one hundred times the weight of steam per revolu- 
tion at release (3) divided by the weight of mixture 
in cylinder per revolution (8). 

1 1 . Pounds of steam per I. H. P. per hour by indicator 
is the weight of steam per revolution at release (3) 
minus the weight of steam per revolution at compres- 
sion (4) multiplied by the revolutions per hour and 
divided by the I.H.P. 



STEAM-ENGINE TESTING. 21 5 

12. Pounds of steam per I.H.P. per hour by tank is 
the weight of steam used by the engine per hour 
divided by the I.H.P. 

13. Distance equivalent to total revolutions is the 
product of the total number of revolutions by the cir- 
cumference of the drivers in feet divided by the 
number of feet per mile. 

14. Mites per hour is the total miles (13) divided by 
the duration of the test in hours. 

15. Dynamometer horse-power is found by multiply- 
ing the tractive horse-power constant (circumference 
of drivers in feet divided by 33000) by the average 
dynamometer-reading in pounds and by the R.P.M. 

16. Friction of engine in H.P. is the difference 
between the I.H.P. and the dynamometer H.P. (15). 

17. Friction of engine in per cent of I.H.P. is one 
hundred times the friction H.P. (16) divided by the 
I.H.P. 

18. Dynamometer work in foot-tons per pound of 
steam by tank is found by dividing the distance run in 
miles (13) by the total weight of steam by tank and 
multiplying the result by 5280, giving the distance run 
in feet on one pound of steam by tank. This distance 
multiplied by the dynamometer-reading in pounds 
and divided by 2000, the number of pounds per ton, 
gives the desired result. 

19. Dynamometer ivork ill foot-tons per pound of dry 
coal is found as above, using total weight of coal in 
place of steam. 

20. Equivalent weight of train in tons is found by 
dividing the corrected dynamometer-reading in pounds 
by the number of pounds assumed to be necessary to 
draw one ton (see Section 185). 



2l6 ENGINEERING LABORATORY PRACTICE. 

2 I . Equivalent number of loaded cars is the total 
weight of train (20) divided by 33, the assumed weight 
in tons of a loaded car. 

22. Equivalent ton-miles is the product of the weight 
of train in tons (20) and the total miles run (13). 

23. Pounds of coal per EH. P. per hour is the total 
pounds of dry coal fired divided by the product of the 
I.H.P. and the duration of the test in hours. 

24. Pounds of standard coal per EH, P. per hour. 
Standard coal is by definition a coal containing 
12,500 B.T.U. per pound. Therefore pounds stand- 
ard coal is to pounds actual coal (23) as the number 
of B.T.U. in a pound of actual coal is to 12,500. 

25. Pounds of coal per EH. P. per hour per square 
foot of" grate-surface is found by dividing the pounds 
of dry coal per I.H.P. per hour (23) by the area of 
the grate-surface in square feet. 

26. Pounds of coal per dynamometer H.P. per hour 
is the total weight of dry coal per hour divided by the 
dynamometer H.P. (15). 

27. Pounds of coal per mile run is found by dividing 
the total pounds of dry coal by the total miles run 

(13)- 

28. Pounds of coal per ton-mile is the total pounds 

of dry coal divided by the product of the number of 
tons (20) and the total miles run (13) or by item (22). 

29. Pounds of water evaporated per hour is found 
by dividing the total pounds of water delivered to the 
boiler by the duration of the test in hours. 

30. Pounds of water evaporated per pound of dry 
coal is found by dividing the total pounds of water 
evaporated by the total pounds of coal fired. 

3 1 . Equivalent evaporation from and at 212 F. per 



STEAM-ENGINE TESTING. 2lJ 

pound of dry coal is found by multiplying the actual 
evaporation (30) by the quotient obtained by dividing 
the B.T.U. per pound of water evaporated (34) by 
965.8, which is the number of B.T.U. per pound of 
water evaporated from and at 212 F. 

32. Equivalent evaporation from ioo° E. into steam 
at jo pounds pressure is found by multiplying the 
actual evaporation (30) by the quotient obtained by 
dividing the B.T.U. per pound of water evaporated 
(34) by 1 1 10.2, which is the B.T.U. per pound of 
water evaporated under the above conditions. 

33. Equivalent evaporation from ioo° F. into steam 
at Jo pounds, per square foot of heating- surface is item 
(32) divided by the area of the heating-surface in 
square feet. 

34. B. T. U. per pound of water evaporated, or 
B.T.U. required to evaporate one pound of water 
under the conditions of the test, is represented by the 
expression x x r x + q x — q„ the value of which is found 
as follows: If the boiler-pressure is p x and the tem- 
perature of the feed-water is / 2 , then the heat neces- 
sary to raise a pound of water from temperature /, up 
to and into steam at pressure/, will be q 19 which is 
the heat of the liquid at pressure/,, minus q„ which is 
the heat of the liquid at the temperature / 2 , plus.*", per 
cent of r lf the heat required to vaporize one pound of 
water at the pressure/,, where x x is equal to (1 minus 
the per cent of moisture in steam). (For values of 
r,, q 19 and q^ see steam tables.) 

35. B.T.U. taken up by boiler per minute is the 
B.T.U. per pound of water (34) times the pounds of 
water evaporated per minute. 

36. B. T. U. taken up by boiler per pound of dry 



2l8 ENGINEERING LABORATORY PRACTICE. 

coal is 60 times the B.T.U. taken up by boiler per 
minute (35) divided by the pounds of dry coal fired 
per hour. 

37. B.T.U. taken up by boiler per pound of combus- 
tible is found by multiplying item (36) by the ratio of 
coal to combustible. 

38. B.T.U. per I. H. P. per minute is the B.T.U. 
taken up by boiler per minute (35) divided by the 
I.H.P. 

39. Pounds of coal per square foot of grate -surface 
per hour is the pounds of dry coal per hour divided 
by the area of the grate-surface in square feet. 

40. I.H.P. per square foot of grate -surface is the 
total I.H.P. divided by the grate-surface in square 
feet. 

41. Horse-power of boiler is found by multiplying 
the B.T.U. per pound of water (34) by the pounds 
of water evaporated per hour and dividing by 
(30 X 1 1 10.2), a H. P. being by definition equivalent 
to the evaporation of 30 pounds of water per hour at 
100 F. into steam at 70 pounds pressure. 

162. Test of Combined Engine and Boiler. — This 
test, embodying the elements of tests of large steam- 
plants, gives the student practice which will fit him 
to conduct the more elaborate tests. The plant con- 
sists of a small combined engine and boiler, the former 
provided with friction-brake and indicator-rig and the 
latter with calibrated feed-barrels and platform scales 
for weighing coal. A convenient arrangement of feed- 
barrels is to provide two barrels, one of which receives 
the supply through a suitable valve. This barrel is 
provided with a discharge-valve and an overflow-pipe 
and is calibrated to the top of the overflow. The 



STEAM-ENGINE TESTING. 219 

second barrel fitted, with a gage-glass, is placed under 
the first barrel and receives its discharge. This barrel 
supplies the boiler. Since the plant is small, the 
method of conducting the test should be the Alternate 
Method prescribed by the American Society of 
Mechanical Engineers. 

Specific Directions. — Two students will be assigned 
to this test. On the day of the test they will be 
assigned two assistants, to whom they may detail such 
observations as they choose. The necessary accessory 
apparatus is an indicator, speed-counter, thermometers 
for feed- and room-temperature, and a whistle. In 
making preparations to start the test the following 
order of procedure should be observed : 

1. Secure the accessory apparatus mentioned above. 

2. Prepare blank log. 

3. Assign observers according to the schedule given 
below. 

4. Place the indicator in position; fill oil-cups and 
lubricator, the former with engine-oil, the latter with 
valve-oil. 

5. Determine upon brake load to be carried. 

6. Weigh out a box of coal, broken to proper size. 

7. Start the test as directed below. 

The following list of assignments is recommended: 
1. Log, time, and misc. observations 



, in charge. 

2. rireman ) 

3. Cards, brake load, and weight of coal. 

4. Speed and weight of water. 

The Log should contain the following items: 

1. Time. 

2. R.P.M. 

3. Brake load. 



220 ENGINEERING LABORATORY PRACTICE. 

4. Boiler-pressure. 

5. Barometer. 

6. Temperature of feed. 

7. Temperature of room. 

8. Pounds of water delivered to boiler. 

9. Pounds of water lost from boiler (leakage and 
other loss). 

10. Pounds of dry coal fired. 

Having the apparatus in good working order, indi- 
cator in place, brake adjusted, oil-cups filled, and 
steam at the working pressure, start the engine, open- 
ing the throttle wide after a few minutes' run, and 
adjust the brake load to the amount previously deter- 
mined upon. Start the test by taking the time, 
placing the marker on the w r ater-level in boiler and in 
lower feed-barrel, and taking all observations except 
cards. The fireman should begin to fire from weighed 
coal and should note the depth and general condition 
of the fire, so that they may be duplicated at the end 
of the test. He should clean the ash-pan immediately 
after the start. The feed-measurer should, imme- 
diately after the start, fill the upper barrel to the point 
of overflow before beginning to replenish the lower 
barrel. During the test he should be careful to drain 
the upper barrel thoroughly before closing the drain- 
valve. 

The test should be from two to four hours in dura- 
tion. Observations should be taken every ten minutes 
and cards every fifteen minutes, the first to be taken 
five minutes after the start. Keep all conditions as 
constant as possible during the test. Watch the 
lubrication carefully and add a little water to the 
brake-wheel from time to time to supply that lost by 



STEAM-ENGINE TESTING. 221 

evaporation. The fireman should seek to maintain an 
even steam-pressure and depth of fire and to keep the 
injector running continuously if possible. 

Just before the close of the test see that the con- 
dition of the fire is the same as at the start and regu- 
late the injector so that in the remaining minutes the 
water in the boiler will reach the initial level. Have 
the level in the lower feed-barrel slightly below the 
initial level. Stop the test by taking all observations 
except speed and shutting down the engine. Bring 
the water-level in the lower feed-barrel back to the 
starting-point and note the fraction of the contents of 
the upper barrel which has been used. Start the in- 
jector and fill the boiler to the third gage-cock. 
Clean the ash-pan and weigh the ash collected. Rake 
down the fire left on the grate into the ash-pan. 
Return all wrenches and oil-cans to their proper 
places, fill the feed-barrels, and leave the engine, 
boiler, and surroundings in good order. 

The Report should cover the following: 

Constants. 

Date of test. 

Name of maker of engine. 

Diameter of cylinder. 

Stroke of piston. 

Diameter of piston-rod. 

H.E. 



Engine-constant 

Radius of brake-arm. 
Weight of brake-arm. 
Diameter of boiler. 
Number of tubes. 
Diameter of tubes. 



222 ENGINEERING LABORATORY PRACTICE. 

Length of tubes. 

Distance from grate to lower tube-sheet. 

Area of grate-surface. 

Area of heating-surface. 

Ratio of grate- to heating-surface. 

Running Log. — In addition to the items given on 
page 219 under this head the following: 

Quality of steam (assumed 98 per cent dry). 

Pounds of water delivered to engine (see note 
on page 223). 

Kind of coal. 

Pounds of ash. 

Calculated Results. — a. M.E.P. H.E 

C. E Average 

b. Indicated horse-power. H.E C.E 

Total 

c. Brake horse-power. 

d. Frictional horse-power. 

e. Same in per cent of I.H.P. 

/. Pounds dry steam per I.H.P. hour by tank 
(Section 161, item 12). 

g. Pounds of coal per I.H.P. hour (Section 161, 
item 23). 

h. Pounds of water evaporated per pound of coal 
(Section 161, item 30). 

i. Equivalent evaporation from and at 212 F. 
(Section 161, item 31). 

j. Horse-power of boiler (Section 161, item 41). 

The Report should be accompanied by a sample pair 
of cards. 

The directions for working up the cards for M.E.P. 
and horse-power will be found in Sections 129 and 



STEAM-ENGINE TESTING. 223 

The item pounds of water delivered to engine is the 
pounds delivered to boiler, as shown by the Running 
Log, minus the loss by leakage and through the calo- 
rimeter, if one be used. 



CHAPTER XIII. 
TESTING OF HYDRAULIC MACHINERY. 

163. Tests of Steam-pumps. — The methods of 
arranging for and conducting tests of steam-pumps 
vary with the design of the plant and the data which 
it is desired to obtain. The method here described 
applies to a comparatively small plant fitted with a 
condenser.* 

Both the steam- and water-cylinders of the pump 
should be fitted with indicators. If the pump is of 
the ordinary direct-connected type without fly-wheel, 
provision should be made to make regular observa- 
tions of the length of stroke. This may easily be 
accomplished by fastening a pencil to the cross-head 
and preparing a board with strips of tough paper of 
suitable length so that the pencil may draw a line on 
the paper equal in length to the stroke. Provision 
must be made for measuring the quantity of water 
delivered and of regulating and determining the suc- 
tion- and delivery-heads. The measurement of the 
water delivered may be accomplished by allowing it 
to flow over a suitable weir or through an orifice the 
coefficients of discharge of which are known. 

Specific Directions. — The number of observers 

*For directions for conducting elaborate tests see report of 
committee of A. S. M. E., Trans., vol. xn. p. 530. 

224 



TESTING OF HYDRAULIC MACHINERY. 225 

needed is eight and they should be distributed as 
follows: 

1. Los: and time ) . . 

■r^ 1 1 1 r in charge. 

2. Discharge-head ) 

3. Speed and length of stroke. 

4. Quantity of water delivered (hook-gage). 

5. Indicators, steam end. 

6. Indicators, water end. 

7. Weight of condensed steam. 

8. Miscellaneous observations. 

The Log should be made out to include the fol- 
lowing observations: 

1. Time. 

2. Speed (double strokes per minute). 

3. Length of stroke. 

4. Steam-pressure. 

5. Barometer. 

6. Delivery-head. 

7. Suction-head. 

8. Temperature of discharge. 

9. Temperature of room. 

10. Volume of water discharged (hook-gage). 

11. Weight of condensed steam. 

The test should be at least an hour long, with obser- 
vations every five minutes. The conditions of the 
test should be maintained for fifteen or twenty minutes 
before the test commences. Consult the instructor 
for conditions of head and speed. 

Observe the usual precautions in starting the test. 
Maintain all conditions as nearly constant as possible 
during the test. 

The Report should include, beside a copy of the 
Running Log, the following items: 



226 ENGINEERING LABORATORY PRACTICE. 

Kind of pump. 
Name of maker. 
Dimensions and constants, 

a. Duration of test 

b. Speed (double strokes per minute), average. 

c. Boiler-pressure, average. 

d. Delivery-head, average. 

e. Suction-head, average. 

f. Total head, average. 

g. Temperature of delivery, average. 

h. Cubic feet of water delivered per second. 

i. Gallons delivered per 24 hours. 

j. Horse-power delivered as shown by water 
pumped. 

k. Indicated horse-power, steam-cylinder. 

/. Indicated horse-power, water-cylinder. 

m. Mechanical efficiency, (item / -f- item k) X 100. 

11. Ratio of I.H.P. (water end) to delivered H.P., 
(item 7-7- item /) X 100. 

0. Steam per I.H.P. per hour. 

/. Duty. 

q. Slip in per cent of total volume swept through. 

r. Sample cards. 

The slip is found by deducting the volume of water 
pumped in a given time from the volume swept 
through by the pump-plunger in the same time. 

The duty is the number of foot-pounds of work 
delivered by the pump per 1,000,000 B.T.U. supplied. 
Calculate the heat supplied from the amount of steam 
used by the pump and the heat per pound of steam 
at boiler-pressure, assuming 2 per cent of moisture. 

164. Advanced Work on Steam-pumps. — To de- 
termine the relation between duty and head with 



TESTING OF HYDRAULIC MACHINERY. 227 

constant steam-pressure, run a series of three tests at 
constant steam-pressure and throttle-opening and with 
varying heads. 

To determine the relation between duty and steam- 
pressure, run a series of three tests at constant head 
and throttle-opening and with steam-pressures rang- 
ing from 80 to 150 pounds. 

Let the tests be conducted and worked up as speci- 
fied in the preceding section. The Report should 
include a statement of the purpose of the tests, a 
description of the plant, a statement of the constant 
conditions, a copy of all observed and calculated data, 
a comparison of results in tabular and graphic form, 
and conclusions. 

165. Tests of Centrifugal Pumps. — The test in- 
volves the measurement and comparison of the power 
supplied the pump and that delivered by the pump. 
The former quantity may be measured by some form 
of transmission-dynamometer (see Section 70). The 
delivered power is computed from the quantity of 
water delivered and the total head against which the 
pump works. 

Specific Directions. — Provide a suitable dynamom- 
eter to measure the power supplied, means for con- 
trolling and measuring the head, and a weir-tank to 
measure the quantity of water delivered. The aux- 
iliary apparatus needed is a whistle, two speed- 
counters, and a thermometer. 

Prepare a Running Log with the following headings : 

1. Time. 

2. Discharge-head. 

3. Suction-head. 

4. Dynamometer- reading. 



228 ENGINEERING LABORATORY PRACTICE. 

5. Cubic feet of water delivered (hook-gage). 

6. Speed of pump. 

7. Speed of dynamometer. 

8. Temperature of water. 

The Log should cover the above observations, to- 
gether with the discharge-pressure and the position of 
the discharge-valve, indicated by the number of turns 
it is open. 

The test should be from one hour to one hour and 
a half in duration, with observations every five 
minutes. The conditions of the test should be main- 
tained for ten minutes before the test commences. 
For conditions of head consult the instructor. 

The Report should include, beside a copy of the 
Running Log, the following items: 

a. Duration of test. 

b. Total head. 

c. Average speed of pump. 

d. Position of gate-valve. 

e. Average temperature of water. 

f. Cubic feet of water pumped per second. 

g. Gallons pumped per hour. 

//. Horse-power delivered by pump. 

i. Horse-power supplied. 

j\ Efficiency of pump. 

In case a line of counter-shafting is interposed 
between the dynamometer and the pump the pump- 
belt should be thrown off and a friction test made of 
the power absorbed by the counter-shafting. This 
should be subtracted from the horse-power as shown 
by the dynamometer to find that absorbed by the 
pump (item i). In calculating the horse-power de- 
livered by the pump (item k) notice should be taken 



TESTING OF HYDRAULIC MACHINERY. 229 

of the temperature of the water as affecting its specific 
weight. 

166. Advanced Work on Centrifugal Pumps. — To 
investigate the relation of the efficiency of the pump 
to the head, run a series of three tests, the first to be 
under as low a head as can be obtained, the third to 
be under as high a head as can be obtained, and the 
second to be under a head midway between the first 
and third. 

The tests should be twenty to thirty minutes in 
duration, the conditions to be maintained for ten 
minutes before the test begins. 

The Report should include a statement of the pur- 
pose of the tests, sketch and description of apparatus, 
a statement of constant conditions, a copy of all 
observed and calculated data (as per Section 165), a 
comparison of results, including a curve showing rela- 
tion between efficiency and total head, and conclusions 
as to the head at which maximum efficiency is obtained 
and the delivery of the pump at that head. 

167. Tests of Turbine-wheels . — The method of 
testing prescribed in this section applies to turbine- 
wheels belonging to the classification known as re- 
action turbines, in which the system of piping in 
which the wheel is located is filled completely from 
high level to low level with water. The test involves 
the measurement and comparison of the power sup- 
plied and that delivered. 

In Fig. 55 is shown a well-known form of turbine- 
wheel with housings. 

Specific Directions. — The power supplied is deter- 
mined from a consideration of the quantity of water 
used by the wheel and the head under which it 



230 



ENGINEERING LABORATORY PRACTICE, 



operates. Provision should be made in the plant for 
controlling and measuring the head and a weir-tank 




Fig. 55. — Leffel Turbine-wheel and Housing. 

provided to measure the quantity of water used. 
The delivered power is measured by a suitable Prony 
brake. The auxiliary apparatus needed is a whistle, 
a speed counter, and a thermometer. 

Make out the Running Log to cover the following 
observations: 

1. Time. 

2. Head. 

3. Speed. 

4. Brake load. 

5. Hook-gage. 



TESTING OF HYDRAULIC MACHINERY. 23 1 

6. Temperature of water. 

7. Gate-opening. 

The test should be from forty-five minutes to one 
hour in duration, with observations every five minutes, 
the conditions of the test to be maintained for ten 
minutes before the test begins. For conditions of 
head and load consult the instructor. 

The Report should include, beside a copy of the 
Running Log, the following: 

a. Duration of test. 

b. Average total head. 

c. Average speed. 

d. Cubic feet of water used per second. 

e. Pounds of water per minute. 
/. Horse-power supplied. 

g. Horse-power delivered. 

h. Mechanical efficiency. 

t. Velocity of water due to head. 

j. Velocity of periphery of wheel. 

Since the turbine receives not only the effect of the 
pressure-head, measured from the center of the wheel 
to the level of water in the head-race, but also that of 
the suction-head, measured from the center of the 
wheel to the level of water in the tail-race, the total 
head (item b) is the difference of level between the 
head-race and the tail-race. 

In calculating the pounds of water discharged per 
minute (item e) notice should be taken of the tem- 
perature of the water as affecting its specific weight. 

168. Advanced Work on Turbines.— To investi- 
gate the relation of head and speed to efficiency, run 
three series of tests, the first to be at a low head, the 
third at a high head, and the second intermediate. 



232 ENGINEERING LABORATORY PRACTICE. 

Each series should consist of three tests at different 
brake loads. 

Each test should be of from 20 to 30 minutes' dura- 
tion, conditions to be maintained for 10 minutes pre- 
vious to each test. 

The Report should include a statement of the pur- 
pose of the tests, a sketch and description of the plant, 
a statement of the constant conditions, a copy of all 
observed and calculated data (as per Section 167), a 
comparison of results, including curves showing the 
relation of efficiency to speed with constant head and 
to head with constant speed, and conclusions as to 
conditions of speed and head giving maximum effi- 
ciency. 

169. Tests of Impulse-wheels. The Pelton 
Wheel. — The Pelton water-wheel consists of a series 
of buckets of special form, secured to the periphery 
of a wheel, and receiving the impact of a jet of water. 



Fig. 56. — Pelton Bucket. 

The form of the bucket is shown in Fig. 56, from 
which it is seen that the jet on striking the bucket is 
divided by the central rib into two portions, each 
branch being diverted on curves designed to secure 



TESTING OF HYDRAULIC MACHINERY. 



233 



the maximum efficiency of the jet. Fig. 57 shows 
the wheel with housing removed. 



r 



-\ 








^Ir 


. <^yp|r 






•tit:;;' . 


f 




: '■'-■■' - si 

1 ' --"' <: ' 


w 





o 
o 

— 

w o 

C <j 

*Q 

|3 



u 

I 

H 
u 

w 



o 
h 

H 






In arranging the wheel for testing it should be 
provided with a suitable brake and means for measur- 



234 ENGINEERING LABORATORY PRACTICE. 

ing the head under which the water is delivered. 
This may be conveniently done by delivering the water 
into a small stand-pipe from which, by a short connec- 
tion, the wheel is supplied. The stand-pipe should 
be arranged with an air-chamber at the top, a gage- 
glass to show the exact level of the water, and a gage 
at the top of the air-chamber to measure the pressure 
at the water-level. A small cock should also be pro- 
vided to adjust the water-level if necessary by allow- 
ing air to escape. The head on the wheel will be the 
gage-pressure reduced to an equivalent head plus the 
actual head of water measured from the center of the 
nozzle to the water-level in the stand-pipe. 

Specific Directions. — Run a number of tests at con- 
stant head and variable brake load. Let the first load 
be as light as can be conveniently run. Let the 
second, third, etc., be under such loads as will suc- 
cessively reduce the speed by steps of ioo revolutions 
per minute. For conditions of head consult the in- 
structor. 

The tests should be of twenty minutes' duration, 
with observations every two minutes. The observa- 
tions to be taken are: 

i. Log and time. 

2. Speed and load. 

3. Head. 

The Report should include, beside a copy of the 
Running Log, the following for each test: 

a. Duration of test. 

b. Effective diameter of bucket-wheel in inches. 

c. Effective diameter of brake-wheel in feet. 

d. Area of nozzle in square feet. 

e. Average height of water in feet. 



TESTING OF HYDRAULIC MACHINERY. 235 

f. Average pressure on gage. 

g. Average total head. 
h. Average speed. 

i. Average net brake load. 

/. Foot-pounds of work delivered per minute. 

k. Horse-power. 

/. Cubic feet of water used per second. 

m. Same in pounds per minute. 

n. Foot-pounds of work done by water per minute. 

o. Efficiency of motor. 

In connection with the Report plot a curve show- 
ing the variation of efficiency with speed. The quan- 
tity of water used may be found by referring to 
Section 23, using 0.95 as the coefficient of discharge. 
The efficiency is 100 times the foot-pounds delivered 
per minute divided by those supplied. 

170. Advanced Work. — For a more thorough in- 
vestigation of the relation of efficiency to head and 
load the following tests should be run: 

To determine the efficiency under different heads, 
run five series of tests as explained above, at heads of 
60, 80, 100, 120, and 140 feet, each series to consist 
of three tests at different loads. The range of loads 
for the different series should be constant. 

The duration of all tests should be twenty minutes, 
with observations every two minutes, the conditions of 
the test to exist five minutes before the test begins. 

The Report should include a statement of the pur- 
pose of the tests, a sketch and description of the 
plant, a statement of constant conditions, a copy of 
all observed and calculated data (see Section 169), and 
a comparison of results, with curves showing variation 
of power and efficiency with head and speed. 



CHAPTER XIV. 
MISCELLANEOUS TESTS. 

171. Tests of Gas-engines. — The purpose of the 
test is to determine the indicated and brake horse- 
power and the cubic feet of gas consumed per indicated 
horse-power per hour under different conditions of 
load, gas mixture, and jacket-temperature. 

Specific Directions. — The test should be one hour in 
length, with observations every five minutes, except 
cards, which should be taken at ten-minute intervals. 
The observations should include: 

1. Time. 

2. Revolutions per minute. 

3. Explosions per minute. 

4. Brake load. 

5. Final temperature of jacket. 

6. Cubic feet of gas. 

7. Cubic feet of air. 

To start the engine (the following is applicable to 
an Otto engine): 

Fill the oil-cups and oil around. 

See that the battery is in good condition and test 
the spark by placing the ignition-points in the cylinder 
in contact with each other and moving the gas-valve 
handle back and forth. A spark should appear when 
the sliding contact is broken. 

236 



MISCELLANEOUS TESTS. 237 

Turn on cooling water to the jacket. 

Prop up the governor by the small pawl under the 
governor-arm. 

Open the gas-valve and turn the engine over by 
hand. Throw off the arm which operates the igniter 
and make the contact at the right moment by hand. 

After the engine is fairly started throw in the igni- 
tion-rod. 

Adjust the brake to give the desired load. 

During the test remove the indicator-piston fre- 
quently and oil it well. Note carefully the sequence 
of the explosions and identify the different cards 
made by the 1st, 2d, 3d, etc., explosions. 

To stop the engine, close the gas- valve and break 
the battery-connections. Turn off jacket cooling- 
water and drain the jacket. 

The Report should include, in addition to a copy 
of the Running Log and sample cards, the following 
items: 

Dimensions and constants. 

a. Duration of test. 

b. Speed. 

c. Average jacket-temperature. 

d> Ratio of explosions to revolutions. 

e. Sequence of explosions. 

f. Ratio of gas to air in the explosive mixture. 

g. Mean effective pressure. 
h. Maximum pressure. 

i. Indicated horse-power. 
j Brake horse- power. 
k. Frictional horse-power. 
/. Cubic feet of gas per I.H.P. per hour. 
As subjects for advanced study the following 



2 3 8 



ENGINEERING LABORATORY PRACTICE. 



changes may be investigated : change of efficiency with 
load, speed, temperature of jacket, and gas mixture. 

172. Tests of Air-compressors. — The extended 
use of compressed air for the transmission of power 
and its exclusive use for special purposes, such as the 
air-brake, gives frequent occasion for the testing of 
air-compressing plants of various kinds. These tests 




Throttle 



Compressor - 1 



Air Valve 



Small 
Receiver 



— Orifice 



Exhaust 



Cooling 
Water 



Condenser 



Condensed 
Steam 



Fig. 58. — Arrangement of Compressor Plant. 

are usually to determine the volume of air delivered 
per pound of steam at various pressures of delivery 
and the pounds of steam consumed per horse-power 
of work delivered. To give practice in the testing of 
compressors working under different conditions, this 



MISCELLANEOUS TESTS. 239 

test may be run either as a continuous test, the condi- 
tions being those under which compressed-air power- 
plants operate, or as an intermittent test, representing 
the working conditions of an air-brake pump. The 
plant consists of the compressor, a surface-condenser 
which receives the exhaust-steam, a large main receiver 
into which the air-cylinder discharges, and an auxiliary 
receiver into which the main receiver leads and which 
contains an orifice of known diameter for measuring 
the discharge of air. In Fig. 58 is shown an arrange- 
ment of piping which has been used in the Purdue 
laboratory with satisfactory results. 

Specific Directions : Continuous Test. — This test 
should be conducted by two men, to whom two assist- 
ants are assigned. The following is a recommended 
assignment of observers: 

1. Log and time ) . 

2. Weight of condensed steam ; ^ 

3. Speed. 

4. Miscellaneous observations. 

The Running Log should be drawn up to contain 
the following items: 

1. Time. 

2 . Steam-pressure. 

3. Main-receiver pressure. 

4. Auxiliary-receiver pressure. 

5. Barometer. 

6. Speed of compressor (double strokes). 

7. Temperature in auxiliary receiver. 

8. Temperature of room. 

9. Weight of condensed steam. 

In case a speed-recorder is not attached it may be 
found convenient to keep the record of speed on a 



240 ENGINEERING LABORATORY PRACTICE. 

separate log-sheet, the observer detailed to count the 
same making a mark for each double stroke. The 
speed should be counted continuously for five minutes 
at a time, beginning at intervals ten minutes apart. 

The accessory apparatus needed for the test is a 
thermometer and a whistle. The test should be one 
hour in duration and observations should be taken 
every five minutes. 

Conduct the test as follows: Carefully inspect the 
piping and see that all valves are suitably placed. See 
that the lubricator is filled and adjusted. Having the 
Running Log prepared and observers posted, start the 
compressor and turn cooling water on the condenser, 
regulating the supply-valve to obtain the amount 
necessary to prevent the escape of uncondensed steam. 
See that the weighing-tanks are empty and the dis- 
charge-valve open. Secure the desired pressure of 
delivery in the main receiver by manipulation of the 
valve between the main and the auxiliary receiver and 
keep it constant during the test. 

Start the test by noting the time, taking all obser- 
vations, closing the weighing-tank drain-valve, and 
noting the water-level as shown by the float or gage- 
glass on the tank. Keep all conditions constant dur- 
ing the test. 

Specific Directions : Intermittent Test, — This test 
should be conducted by two men with two assistants. 
The following is a recommended assignment of ob- 
servers : 

1. Log and time ) . 

2. Weight of condensed steam ; 
^3. Speed. 

4. Miscellaneous observations. 



MISCELLANEOUS TESTS. 24I 

The Running Log should be drawn up to cover the 
following items: 

1. Time of starting compressor. 

2. Time of stopping compressor. 

3. Steam-pressure. 

4. Main-receiver pressure, maximum. 

5. Main-receiver pressure, minimum. 

6. Auxiliary-receiver pressure. 

7. Barometer. 

8. Speed of compressor (double strokes). 

9. Temperature of auxiliary receiver, 
■io. Temperature of room. 

11. Weight of condensed steam. 

The test should be one hour in duration, and obser- 
vations should be taken at the time of starting and 
stopping the compressor, except in the case of items 
3, 6, and 9, which should be taken at intervals while 
the compressor is at work. The speed (item 6) is 
determined by counting the number of double strokes 
for the interval during which the^ compressor is run- 
ning. 

Conduct the test as follows: Carefully inspect the 
piping and see that all valves are suitably placed. 
See that the lubricator is filled and adjusted. Having 
the Running Log prepared and observers posted, 
start the compressor and turn cooling water on the 
condenser, regulating the supply-valve to obtain the 
amount necessary to prevent the escape of uncon- 
densed steam. See that the weighing-tank is empty 
and its discharge-valve open. With the throttle-valve 
wide open, regulate the auxiliary-receiver pressure to 
give a main-receiver pressure of five pounds in excess 
of the maximum pressure determined upon. This 



242 ENGINEERING LABORATORY PRACTICE. 

auxiliary-receiver pressure should be constantly main- 
tained throughout the test by manipulation of the 
main-receiver discharge-valve. Now stop the com- 
pressor and allow the main-receiver pressure to fall. 
When the pressure has fallen to the predetermined 
minimum the compressor should be started with wide- 
open throttle and the test considered as commenced. 

The method of procedure now is to allow the com- 
pressor to raise the main-receiver pressure to the pre- 
determined maximum, then shut down quickly and 
allow the pressure to fall to the minimum, always 
keeping the auxiliary-receiver pressure constant. 
Then start the compressor and repeat the process 
throughout the test. The test is to be stopped when, 
after shutting down the compressor, the main-receiver 
pressure has fallen to the minimum. 

Report of Compressor Test. — The Report should 
include the following: 

a. Weight of air escaping per second, in pounds. 

G = o.5 3 oF^ when A > 2 A > • ■ • (0 



G= i.o6oF^/ P ^ P ' t A) when /,<*>.. ( 2 ) 

where A is the mean pressure in the small receiver in 
pounds per square inch absolute, p a the barometric 
pressure in pounds per square inch, T, the absolute 
temperature of the air in the small receiver in degrees 
Fahrenheit, and F the area of the orifice in square 
inches. Use formula (i) or (2) according as A may 
be greater or less than 2p a . 



MISCELLANEOUS TESTS. 243 

b. Pounds compressed per minute, 

P=GX 60 (3) 

c. Total weight compressed, 

P y = P X no. of minutes of entire test. . (4) 

d. Volume of one pound of atmospheric air in 
cubic feet, 

53-227; ,. 

'•"^ST' (5) 

where T a is the absolute temperature of the room in 
degrees Fahrenheit. 

e. Volume compressed per second, 

V=V a xG (6) 

f. Total volume compressed, 

V 1 — V X no. of seconds of entire test. . (7) 

g. Work done in compressing one pound of air in 
foot-pounds, 

where n = 1.4, and p^ is the mean pressure in the 
main reservoir in pounds per square inch absolute. 
h. Horse-power, 

Wx P 

H - p - = l^ • • • • (9) 

H.P. = *** fht . . (,o) 

33000 X no. minutes that J 

compressor was working 



244 ENGINEERING LABORATORY PRACTICE. 

Formula (9) should be used for continuous and 
formula (10) for intermittent running. 

i. Steam per H. P. per hour 

steam per hour in lbs. 
= - H.P. " " * ' ^ II ' 

j. Air compressed per pound of steam in pounds 

.... (12) 



total steam in lbs. 
k. Volume of air compressed per pound of steam 

V 



total steam in lbs, 



(13) 



/. Volume of standard air compressed per pound 
of steam 

= I2.3QOQ X ,. ^ 1 ^ — TT~ • • ( l 4) 

Jy y total steam in lbs. v ^' 

m. Ratio of volume of air compressed to volume 

swept by piston = V l -^ (volume swept by pistons 

< 

in one stroke X total number of strokes) 

. . . (15) 



C X no. of strokes 



The value of the constant C in formula (15) may be 
had by reference to the laboratory Commonplace- 
book. 

The volume of standard air, that is, air at 32 F. 
and under atmospheric pressure as given by formula 
(14), will serve as a basis of comparison between differ- 
ent tests. The constant 12.3909 is derived from 
formula (5), making T = 32 -\- 460.7 and/ a = 14.7. 



MISCELLANEOUS TESTS. 245 

173. Advanced Work on Air-compressors. — To 
determine the efficiency under different pressures of 
delivery, run a series of four tests under constant 
steam-pressure. Let the conditions be as follows: 

1st. Continuous running with air-pressure as high 
as pump will deliver. 

4th. Continuous running with air-pressure as low as 
can be had without using more steam than can be 
readily condensed. 

2d and 3d. Continuous running with air-pressure 
intermediate between that of 1st and 4th tests. 

All tests should be of 30 minutes' duration, and the 
conditions should be maintained for ic minutes before 
beginning the test. They should be conducted and 
worked up as explained in Section 172. 

The Report should include a statement of the pur- 
pose of the test, a sketch and description of the plant, 
a statement of the constant conditions, a copy of the 
Running Log, a tabulated summary statement of the 
calculated results, and a comparison of results, includ- 
ing curves showing the relation of horse-power, 
steam per horse-power-hour, cubic feet of air pumped 
per second and per pound of steam to pressure of 
delivery. 

To determine the efficiency under different steam- 
pressures, run a series of three tests under constant 
pressure of delivery and with steam-pressures of 60, 
120, and 180 pounds. Conduct the tests and make 
the report as described above. 

174. Tests of Injectors. — Description. — The injec- 
tor is an instrument in common use for delivering 
feed-water to boilers. It is used very generally on 
locomotive boilers and to a considerable extent in 



246 ENGINEERING LABORATORY PRACTICE. 

small stationary plants. It is made in two general 
classes, lifting and non-lifting. In the former class 
the water-supply is below the level of the injector and 
work is done in raising the water, in addition to that 
required to deliver against a pressure. In the latter 
class the water is delivered to the injector under more 
or less pressure. 

The lifting injectors may be further divided into 
single- and double-tube injectors. In Fig. 59 is shown 
a sectional view of the Metropolitan double-tube 
locomotive injector. Pipe-connection is made at A 
with the steam-supply, at B with the water-supply, 
and at C with the delivery-pipe. D is the overflow. 
The tubes E are termed the lifting and combin- 
ing tubes and their function is to lift the water from 
the source to the forcing-tubes F, which deliver it 
against the desired pressure. Fig. 60 is a sectional 
view of the Sellers self-acting injector of 1887, a 
single-tube injector. At 19, 23, iga and 29 are, 
respectively, the connections for the steam-supply, 
water-supply, delivery, and overflow. The single set 
of tubes 3-2-1 performs the function both of lifting 
and forcing. 

Operation of the Injector. — The method of starting 
the injectors described above, which applies in a 
general way to many injectors now on the market, is 
as follows: 

Open steam and water-supply valves wide. 

Pull starting-lever back a short distance until water 
appears at the overflow and then continue the move- 
ment steadily as far as the lever will go (Metropoli- 
tan); or pull the starting-lever back steadily as far as it 
will go (Sellers). 



MISCELLANEOUS TESTS. 



247 




248 ENGINEERING LABORATORY PRACTICE. 




tO* 



MISCELLANEOUS TESTS. 249 

Regulate the rate of delivery by the water-supply 
valve. 

Method of Testing. — The testing-plant consists of 
two tanks mounted on scales or fitted with calibrated 
gage-glasses. The injector draws from one and de- 
livers into the other. In order to begin the test with 
a flying start, provision is made by which the injector 
may be started prior to the commencement of the test, 
drawing from the supply-tank and delivering into 
a by-pass fitted with a suitable swinging nozzle. 
The initial level is maintained in the supply-tank 
by an inlet-pipe controlled by a quick-acting valve 
whose handle is connected with the swinging nozzle. 
When the test is begun the supply-valve is closed 
and at the same time the swinging nozzle turns 
the delivery from the by-pass into the delivery-tank. 
Provision is made for producing and measuring 
the head against which the injector is to work and 
for measuring the temperatures of supply and de- 
livery. 

Specific Directions. — Determine upon the steam- 
pressure, pressure of delivery, temperature of supply, 
and rate of delivery under which the test will be made 
by consultation with the instructor. 

Prepare the Running Log, making provision for 
the following list of observations: 

1. Time. 

2. Steam-pressure. 

3. Delivery-pressure. 

4. Barometric pressure. 

5. Temperature of supply. 

6. Temperature of delivery 

7. Temperature of room. 



250 ENGINEERING LABORATORY PRACTICE. 

8. Reading of supply-tank. 

9. Reading of delivery-tank. 

The duration of the test is governed by the capacity 
of the supply-tank, and will vary with the rate of 
delivery. 

Having the discharge-tank empty, the supply-tank 
full, and the regulating-valve on discharge-pipe wide 
open, start the injector, allowing the delivery to flow 
into the by-pass. Open the supply-tank inlet a 
sufficient amount to maintain a constant water-level 
in the supply-tank. When the desired conditions 
are obtained start the test by shutting off the supply- 
valve, turning the delivery into the delivery-tank and 
taking all observations. Take observations at regular 
intervals during the test and keep all conditions con- 
stant. To close the test, stop the injector. 

The following is a form of Report to be used in 
connection with the injector test: 

TEST OF INJECTOR. 



Observers \ Date, 



Make of injector 

Number and style 

Size of connections: steam in.; water in.; dis- 
charge in. 

Diameter (minimum) of lifting-tube. .. .in. ; forcing-tube. .. .in. 

a. Duration of test 

b. Steam-pressure (average), pounds gage, /> t 

c. Delivery-pressure (average), pounds gage, / 2 

d. Delivery-head (average), feet, h x 

e. Suction-head (average), feet, h- 2 

f. Temperature of supply (average), /j 

g. Temperature of delivery (average), 2" 2 

h. Pounds water supplied per hour, W\ 



MISCELLANEOUS TESTS. 2$ I 

i. Pounds water delivered per hour, Wi 

/. Cubic feet of water delivered per hour, c 

k. Wet steam per hour, zu k 

/. Dry steam per hour, w 2 

m. Water delivered per pound wet steam, pounds 

n. Water delivered per pound dry steam, pounds 

o. Velocity of discharge, feet per second, v 

/. Energy delivered, raising injection-water, B.T.U. per hr 

q. Energy delivered, heating injection-water, B.T.U. per hr 

r. Energy delivered, velocity of discharge, B.T.U. per hr 

s. Total energy delivered, B.T.U. per hour 

t. Energy supplied, B.T. U. per hour 

u. Thermal efficiency 

v. Horse-power 

w. Dry steam per horse-power per hour, pounds 

The wet steam per hour, w 1 = W^ — W x . 

The dry steam per hour, w^ = x 1 w l , where x x is 
the per cent of dry steam. If this is not measured 
assume 98 per cent. 

The water delivered per pound of wet steam = W^ 

The water delivered per pound of dry steam = W q 
-f- w 2 . 

The velocity of discharge, 

c X 144 



v = 



3600 X (area discharge end in sq. in.)' 



The energy of raising injection-water = [WJJi x -\-h^ 
+ wji^ + 77%. 

The energy of heating injection-water = W x (q 2 — q x ), 
where q x and q 2 correspond to t x and t % . 

The energy of discharge = Wj? -f- (2g X 778). 

The total energy delivered = item / -f- item q -\- 
item r. 



252 ENGINEERING LABORATORY PRACTICE. 

The energy supplied = w l (x 1 r l -f- q x — q^) y where 
r, and q x correspond to /, , and q 2 corresponds to / 2 . 

-T-i i i m • item s 

lhe thermal efficiency = ioo X • 

J item / 

Tll . w x {K + h % ) + w x h x 

The horse-power == -p . 

v 6o X 33°oo 

The dry steam per horse-power per hour = ze/ 9 -f- 
item v, 

175. Advanced Work on Injectors. — As topics for 
advanced study of injectors the following are sug- 
gested : 

1. Effect of steam-pressure on efficiency and 
capacity. 

Run a series of five tests under the following con- 
ditions: steam-pressures of 60, 80, 100, 150, and 200 
pounds; rate of discharge minimum, mean, or maxi- 
mum ; feed-temperature constant and delivery-pressure 
equal to steam-pressure. 

2. Effect of temperature of feed on efficiency and 
capacity. 

Run a series of five tests under the following condi- 
tions: feed-temperatures of 50, 80, no, 140, and 
maximum; steam-pressure constant; mean rate of 
delivery and delivery-pressure equal to steam-pres- 
sure. 

3. Effect of delivery-pressure on efficiency. 

Run a series of three tests under the following con- 
ditions: delivery-pressure 75 and 100 per cent of 
steam-pressure and maximum; mean rate of delivery; 
steam-pressure and feed-temperature constant. 

4. Maximum starting and working temperatures. 
Make an experimental investigation under different 

steam-pressures. 



MISCELLANEOUS TESTS. 



253 



5. Overflow loss under different steam-pressures. 

6. Restarting conditions. 

These tests (except under heads 4, 5, and 6) should 
be run and worked up as described in Section 174. 
The Report should include a statement of the purpose 
of the tests, a sketch and description of the plant, a 
statement of the conditions of the tests, a copy of all 
observed and calculated data, comparisons of results 
accompanied by curves, and conclusions. 

176. Tests of Steam-turbines. The De Laval 
Turbine. — The De Laval steam-turbine consists of a 
wheel provided with buckets, against which act jets of 
steam delivered from suitable nozzles. The wheel is 




ELEVATION 



I Turl 



n 



Turbine Wheel •' ',' }j 2 • 




PLAN 



Fig. 61. — De Laval Steam-turbine. Arrangement of 
Wheel and Nozzle. 

mounted upon a shaft carrying a small pinion which 
meshes with a large gear on the driving-shaft, thus 



254 ENGINEERING LABORATORY PRACTICE. 

reducing the speed at which the power is delivered. 
The speed is regulated by a throttling-governor. 

In Fig. 6 1 is shown the arrangement of nozzle and 
wheel, and in Fig. 62 are shown dimensioned drawings 
of the moving parts of a 10-horse-power turbine. 
The form of the nozzle is such that the steam in 
passing through is expanded to atmospheric pressure, 
while its velocity is correspondingly increased. The 
energy in the steam is thereby converted into the 
form most available for impact on the wheel. In the 
10-horse-power turbine there are four nozzles, two of 
which are provided with stop-valves. Nozzles of 
different sizes are provided for use with different 
steam-pressures, as follows: 

No. 1. No. 2. No. 3. No. 4. 

For 100 lbs. (7 kgm.)) 5 x7.1mm. 5X7-10101. R] . . 

use nozzles marked f (with stopper). (with stopper). 5 x 7 ' x mm ' oiina. 

I3 olbs.( 9 . 2 kgm.)[ (^sto^er). (with re^spindle). 4 X 6.3 mm. 4 X 6.3 mm. 

x 4 olbs.( 9 .8kgm.)[ (w ^ h 6 st ; m p m r , (1 &&5£> 4X6.3 mm. 4 X 6.3 mm. 

x8olbs.( I2 .7k g m.)f ^£5^ ik&S*. 3.7X6mm. Blind. 

When using the regulating-spindle with 130 pounds 
pressure observe the following directions: On the 
spindle nearest the wheel is the mark 09^; here the 
hand must point when the nozzle is used with 130 
pounds pressure. To shut off the nozzle entirely, the 
hand should point to mark 5. On the socket of the 
nozzle and also on the box of the turbine is the mark 
1, showing where the socket and nozzle should be 
placed. In fitting the turbine for testing it should 
be provided with a suitable brake, and should be in 
pipe-connection with a surface-condenser. 



MISCELLANEOUS TESTS. 



255 




,1* 





ft^h 




w 

Section 


1 


5 





lip 

if 




w 

H 
C/) 

■J 

w 
Q 

fa 
o 

C/2 

►J 

s 

w 
Q 



O 

t-H 



256 ENGINEERING LABORATORY PRACTICE. 

Specific Directions. — Run three tests at constant 
steam-pressure and different brake loads to determine 
the variation in economy. The auxiliary apparatus 
needed includes a speed-counter and a whistle. 

The tests should be of 30 minutes' duration, with 
observations at five-minute intervals, the turbine to 
run at least 20 minutes before the first test is com- 
menced, and to run under load conditions of the test 
for five minutes before taking observations. 

The observations are as follows: 

1. Initial steam-pressure. 

2. Pressure below governor- valve. 

3. Exhaust-pressure. 

4. Barometer. 

5. Brake load, net. 

6. Speed. 

7. Weight of condensed steam. 

After determining the desired brake loads under 
which the tests are to run calculate from known 
dimensions of the brake the weight which must be 
carried on the scale to secure the required power. 

The Report should fully state conditions of test, 
giving number and size of nozzles used, and shou'd 
include a brief statement of arrangement of plant, a 
tabulated Running Log, and the following calculated 
results: 

a. Brake H.P. 

b. Weight of steam per H.P. per hour. 

As subjects for advanced study, investigate the 
change of efficiency with change of steam-pressure 
and the effect of varying the number of nozzles in use. 



APPENDIX. 



177. Circumferences and Areas of Circles. 

1 TO 400 ADVANCING BY 10THS FROM 1 TO 50. 

(Abridged from Carpenter's "Experimental Engineering.") 



Diam. 


Circum. 


Area. 


Diam. 


Circum. 
20.106 


Area. 


Diam. 


Circum. 

37-071 


Area. 


1.0 


3.142 


.7854 


6.4 


32.170 


11. 8 


109.36 


1.1 


3-456 


•9503 


6.5 


20.420 


33-183 


11. 9 


37-385 


in. 22 


1.2 


3-77Q 


1.1310 


6.6 


20.735 


34.212 


12.0 


37-699 


113. 10 


*-3 


4.804 


1.3273 


6.7 


21 .049 


35-257 


12. 1 


38.013 


114.99 


1.4 


4.398 


1-5394 


6.8 


21.363 


36.317 


12.2 


38.327 


116.90 


i-5 


4.712 


1.7672 


6.9 


21.677 


37-393 


12.3 


38.642 


118.82 


1.6 


5.027 


2.0106 


70 


21.991 


38.485 


12.4 


38.956 


120.76 


1.7 


5.241 


2.2698 


7- 1 


22 . 305 


39-592 


12.5 


39.270 


122.72 


1.8 


5-655 


2-5447 


7-2 


22.619 


40.715 


12.6 


39.584 


124.69 


1.9 


5-969 


2-8353 


7-3 


22.934 


41.854 


12.7 


39.898 


126.68 


2.0 


6.283 


3.1416 


7-4 


23.248 


43.008 


12.8 


40.212 


128.68 


2.1 


6-597 


3-4636 


7-5 


23.562 


44-179 


12.9 


40.527 


130.70 


2.2 


6.912 


38013 


7-6 


23.876 


45-365 


i3.o 


40.841 


132.73 


2-3 


7.226 


4.1548 


7-7 


24.190 


46.566 


13. 1 


41-155 


T34.78 


2.4 


7-54o 


4.5239 


7 .8 


24 • 504 


47-7 8 4 


13.2 


41.469 


136.85 


2.5 


7.854 


4.9087 


l' 9 


24.819 


49.oi7 


13-3 


41-783 


138.93 


2.6 


8.168 


5.3093 


8.0 


25.133 


50.266 


13-4 


42.097 


141.03 


2.7 


8.482 


5.7250 


8.1 


25.447 


5T.530 


i3-5 


42.412 


i43- T 4 


2.8 


8.797 


6.1575 


8.2 


25.761 


52.810 


13.6 


42.726 


145-27 


2.9 


9. in 


6 . 6052 


8.3 


26.075 


54.106 


13-7 


43.040 


147.41 


3.0 


9-425 


7.0686 


8.4 


26.389 


55.4i8 


13.8 


43-354 


149-57 


3-i 


9-739 


7-5477 


8.5 


26 . 704 


56.745 


13-9 


43.668 


I5I-75 


3-2 


10.053 


8.0425 


8.6 


27.018 


58.088 


14.O 


43.982 


153-94 


3-3 


10.367 


8.553o 


8-7 


27-332 


59-447 


14. 1 


44.296 


156.15 


3-4 


to. 681 


0.0792 


8.8 


27.646 


60.821 


14.2 


44.611 


158.37 


3-5 


10.996 


9. 62 1 1 


8.9 


27.960 


62.211 


14-3 


44-9*5 


160.61 


3-6 


11. 310 


10.179 


9.0 


28.274 


63.617 


14.4 


45.239 


162.86 


3-7 


11 .624 


10.752 


9.1 


28.588 


65-039 


14.5 


45-553 


165.13 


3.8 


xi. 938 


11. 341 


9.2 


28.903 


66.476 


14.6 


45.867 


167.42 


3-9 


12.252 


11.946 


9-3 


29.217 


67.929 


14.7 


46.181 


169.72 


4.0 


12.566 


12.566 


9.4 


29-53 1 


69.398 


14.8 


46.496 


172.03 


4.1 


12.881 


13.203 


9-5 


29.845 


70.882 


14.9 


46.810 


174-37 


4.2 


^•IQS 


13.854 


9.6 


30.159 


72.382 


15 O 


47.124 


176.72 


4-3 


x 3-509 


14.522 


9-7 


30.473 


73.898 


i5-i 


47.438 


179.08 


4.4 


13.823 


*S-SOS 


9.8 


30.788 


75-43° 


15 2 


47-752 


181.46 


4-5 


H-I37 


15.904 


9-9 


31 . 102 


76.977 


15-3 


48.066 


183.85 


4.6 


M-45 1 


16.619 


10. 


31.416 


78 • 540 


15.4 


48.381 


186.27 


♦ •7 


H.765 


17.349 


10. 1 


3 » • 73o 


80.119 


15-5 


48.695 


188.69 


4.8 


15.080 


18.096 


10.2 


32.044 


81.713 


15.6 


49 . 009 


191.13 


4-9 


1 5-394 


18.857 


10.3 


32.358 


83.323 


15-7 


49.323 


193-59 


50 


15.708 


19.635 


10.4 


32.673 


84-949 


15.8 


49-637 


196.07 


5.i 


16.022 


20.428 


10.5 


32.987 


86 . 590 


15.9 


49-951 


198.56 


5-2 


16.336 


21.237 


10.6 


33-3QI 


88.247 


16.O 


50.265 


201 .06 


5-3 


16.650 


22.062 


10.7 


33-6i5 


89.920 


16. 1 


50.580 


203.58 


5-4 


16.965 


22.902 


10.8 


33.929 


91 .609 


16.2 


50.894 


206. 12 


5-5 


17.279 


23-758 


10.9 


34-243 


93-3*3 


16.3 


51.208 


208 . 67 


5.6 


J 7.593 


24.630 


II. 


34.558 


95-033 


16.4 


51.522 


211.24 


5-7 


17.90? 


25.518 


II . I 


34.872 


96.769 


16.5 


51.836 


213.83 


5.8 


18.: - 


26.421 


IT. 2 


35.T86 


98.520 


16.6 


52.150 


216.42 


5-9 


18.535 


27.340 


"•3 


35-500 


100.29 


16.7 


52.465 


219.04 


6.0 


18.850 


28.274 


11,4 


35.8i4 


102.07 


16.8 


52.779 


221.67 


6.1 


19.164 


29.225 


"•5 


36.128 


103.87 


16.9 


53-093 


224.32 


6.2 


19.478 


30.191 


11. 6 


36.442 


105.68 


17.O 


53.407 


226.98 


6.3 


19.792 


31-173 


11. 7 


36.757 


107.51 


17. 1 


53-721 


229.66 



257 



258 ENGINEERING LABORATORY PRACTICE. 

CIRCUMFERENCES AND AREAS OF CIRCLES 



Diam. 


Circum. 

| 


17.2 


54-035 


17-3 


54.350 


17.4 


54.664 


17 5 


54-978 


17.6 


55-292 


17.7 


55.606 


17.8 


55-92Q 


17.9 


56 235 


18.O 


56.549 


18. 1 


56.863 


18.2 


57.177 


18.3 


57-491 


18.4 


57-805 


18.5 


58.119 


18.6 


58.434 


18.7 


58 748 


18.8 


59.062 


18.9 


59.376 


19.0 


59.690 


19. 1 


60 . 004 


19.2 


60.319 


19-3 


60.633 1 


19.4 


60.947 | 


19-5 


61.261 1 


19.6 


6i.575 


19.7 


61.889 


19.8 


62.204 


19.9 


62.^18 


20.O 


62.832 


20. 1 


63.146 


20.2 


63.460 


20.3 


63-774 


20.4 


64.088 


20.5 


64.403 


20.6 


64.717 


20.7 


65-031 


20.8 


65-345 


20.9 


65-659 


21.0 


65.973 


21 .1 


66.288 


21.2 


66 . 602 


21.3 


66.916 


21.4 


67.230 


21.5 


67-544 


21.6 


67.858 


21.7 


68.173 


21.8 


68.487 


21.9 


68.801 


22.0 


69.115 


22.1 


69.429 


22.2 


69-743 


22.3 


70.058 1 


22.4 


70.372 ! 


22.5 


70.686 


22.6 


71 .000 


22.7 


7I-3I4 


22.8 


71.268 


22.9 


71.942 


23.0 


72.257 


23.I 


72.571 

1 



232.35 
235.06 

237-79 
240.53 
243.29 
246.06 
248.85 
251-65 
254-47 
257.30 
260.16 
263.02 
265.90 
268.80 
271 .72 
274-65 
277-59 
280.55 

283.53 
286.52 

289.53 
292-55 
295-59 
298.65 
301 .72 
304.81 
307.91 

3 IX -o3 
314.16 

3*7- 3 1 
320.47 
323.66 
326.85 
330.06 
333-29 
336.54 
339.8o 
343-07 
346.36 
349.67 
352.99 
356.33 
359-68 

363-05 
366.44 

369.84 
373-25 
376.69 
380. 13 
383.60 
387-08 

39o.57 
394.08 
397-6i 
401.15 
404.71 
408 . 28 
411.87 
415.48 
419.10 



Diam. 



23.2 
23-3 
23-4 
23-5 
23.6 

23-7 
23.8 
23.9 
24.O 
24.1 
24.2 
24-3 
24.4 
24-5 
24.6 

24.7 
24.8 
24.9 
25.O 
25.1 
25.2 

25-3 
25.4 

25-5 
25.6 

25-7 

25.8 

25-9 
26.O 

26.1 
26.2 
26.3 
26.4 
26.5 
26.6 
26.7 
26.8 
26.9 
27.O 
27.1 
27.2 

27-3 
27.4 

27-5 
27.6 
27.7 
27.8 
27.9 
28.O 

28. T 

28.2 
28.3 
28.4 
28.5 
28.6 
28.7 
28.8 
28.9 

29 o 

29.1 



Circum. 



72.885 
73-199 
73-5I3 
73.827 
74.142 
74-456 
74.770 
75.084 
75 398 
75-712 
76.027 

76.341 
76.655 
76.969 
77-283 
77-597 
77-9" 
78.226 
78 . 540 
78.854 
79.168 
79.482 
79.796 
80. in 
80.425 
80.739 

81.053 
81.367 
81.681 
81.996 
82.310 
82.624 
82.938 
83.252 
83.566 
83.881 
84.195 
84.509 
84.823 
85.137 
85.451 
85.765 
86.080 
86.394 
86.708 
87.022 
87.336 
87.650 
87.965 
88.279 

88-593 
88.907 
89.221 

89-535 
89.850 
90 . 1 64 
90.478 
90.792 
91.106 
91.420 



Area. 



422.73 
426.39 
430.05 
433 • 74 
437-44 
44i-i5 
444-88 
448.63 
452 .39 
456.17 
459.96 

463.77 
467.60 

47^-44 
475-29 
479.16 
483-05 
486.96 
490.87 
494.81 
498.76 
502 . 73 
506.71 
510.71 
5H-72 
518.75 
522.79 
526.85 
530.93 
535 .02 
539-13 
543-25 
547.39 
55L55 
555.72 
559-90 
564.10 
568.32 
572.56 
576.80 
581.07 
585.35 
589.65 
593.96 
598.29 
602 . 63 
606.99 
611.36 

6i5-75 
620.16 
624.58 
629.02 
633-47 
637.94 
642.42 
646.93 
651.44 

655-97 
660.52 
665.08 



Diam. 


Circum. 


29.2 


91-735 


29-3 


92.049 


29.4 


92.363 


29.5 


92.677 


29.6 


92.991 


29.7 


93 • 305 


29.8 


93.619 


29.9 


93-934 


300 


94-248 


30.1 


94.562 


30.2 


94.876 


30.3 


95.190 


30.4 


95-505 


30.5 


95.819 


30.6 


96.133 


30.7 


96.447 


30.8 


96.761 


30.9 


97.075 


3io 


97-389 


31-1 


97.704 


31.2 


98.018 


3i.3 


98.332 


3*-4 


98.646 


3'-5 


98.960 


31.6 


99.274 


3i-7 


99.588 


31-8 


99.903 


31.9 


100.22 


32-0 


100.53 


32.1 


100.85 


32.2 


101.16 


32.3 


101.47 


32 4 


101.79 


32.5 


102.10 


32.6 


102.42 


32.7 


102.73 


32.8 


103.04 


^2.9 


103.36 


33 -o 


103.67 


33-1 


103.99 


33-2 


10^.30 


33-3 


104 . 62 


33-4 


104.93 


33-5 


105 . 24 


33-6 


105.56 


33-7 


105.87 


33-8 


106. 19 


33 9 


106.50 


34 


106.81 


34-1 


107.13 


34-2 


107.44 


34-3 


107.76 


34-4 


108.07 


34-5 


108.38 


34-6 


108.70 


34-7 


109.01 


34-8 


x °9-33 


34-9 


109.64 


35 


109.96 


35-i 


110.27 



Aiea. 



669.66 
674.26 
678.87 
683.49 
688.13 
692.70 

697-47 
702.15 

706.86 
711.58 
716.32 
721.07 
725.83 
730.62 
735-42 
740.23 
745.o6 
749-91 
754-77 
759-65 
764.54 
769.45 
774-37 
779.31 
784.27 
789.24 
794-23 
799.23 
8°4 • 25 
809.28 

8i4-33 
819.40 
824.48 
829.58 
834.69 
839.82 
844.96 
850.12 
855-30 
860 . 49 
865 . 70 
870.92 
876.16 
881.41 
886.68 

891.97 
897.27 

9°2 • 59 
907.92 
913.27 
918.63 
924.01 
929.41 
934-82 
940.25 
945.69 

951.15 
956.62 
962. 11 
967.62 



APPENDIX. 259 

CIRCUMFERENCES AND AREAS OF CIRCLES. 



Diam. 


Circum. 

110.58 


Area. 


Diam. 


Circum. 
129 43 


Area. 


Diam. 


Circum. 


Area. 


35-2 


973-14 


41.2 


T 333-i7 


47-2 


148.28 


1749.74 


35-3 


110.90 


978.68 


4*. 3 


129-75 


1339.65 


47-3 


148.60 


1757-16 


35-4 


in. 21 


984.23 


4T.4 


130.06 


1346.14 


47-4 


148.91 


1764.60 


35-5 


in. 53 


989.80 


4i-5 


130.38 


1352.65 


47.5 


149-23 


1772.05 


35-6 


in. 84 


995-38 


41.6 


130.69 


i359-i8 


47 6 


149-54 


1779.52 


35-7 


112. 15 


1000.98 


41.7 


1 3 1 . 00 


1365.72 


47-7 


M9 85 


1787.01 


35.8 


112.47 


1006.60 


41.8 


131.32 


1372.28 


47.8 


150.17 


i794-5i 


35-9 


112.78 


1012.23 


41.9 


13^63 


1378.85 


47-9 


150.48 


1802.03 


360 


113. 10 


1017.88 


42. 


131.95 


1385-44 


48.O 


150.80 


1809.56 


36.1 


"3-4 x 


1023.54 


42.1 


132.26 


1392.05 


48.1 


151-11 


1817.11 


36.2 


"3-73 


1029.22 


42 .2 


^2^58 


1398.67 


48.2 


151.42 


1824.67 


36.3 


114.04 


1034.91 


42.3 


132.89 


1405.31 


48.3 


I5I-74 


1832.25 


364 


"4-35 


1040.62 




133.20 


141 1 .96 


48.4 


152.05 


1839.84 


36.5 


114.67 


1046.35 , 


42-5 


J 33-52 


1418.63 


48.5 


1 5-2 -37 


1847.45 


36.6 


T14.98 


1052.09 


42.6 


133.83 


1425.31 


48.6 


152.68 


1855.08 


3 6 «7 


II5-30 


1057.84 | 


42.7 


x 34-i5 


1432.01 


48.7 


153-00 


1862.72 


36.8 


115. 61 


1063.62 j 


42.8 


134.46 


1438.72 


48.8 


153-3 1 


1870.38 


3 6 -9 


115.92 


1069.41 1 


42.9 


134-77 


M45-45 


48.9 


153.62 


1878.05 


37 


116.24 


1075.21 


43 


135-09- 


1452.20 


49.O 


153-94 


1885.74 


37-i 


116.55 


108 1 .03 


43-1 


i35.4o 


1458.96 


49.1 


154.25 


1893.45 


37 2 


116.87 


1086.87 


43-2 


x 35-72 


I465-74 


49-2 


154.57 


1901 .17 


37-3 


117. 18 


1092.72 


43-3 


136.03 


1472.54 


49-3 


154-88 


1908.90 


37-4 


117.50 


1098.58 


43-4 


136.35 


1479-34 


49-4 


155-I9 


1916.65 


37-5 


117. 81 


1104.47 


43-5 


136.66 


1486.17 


49-5 


155.51 


1924.42 


37-6 


118. 12 


1110.36 


43 6 


136.97 


1493.01 


49 6 


155-82 


1932.21 


37-7 


118.44 


1116.28 


43-7 


T 37>29 


1499.87 


49-7 


156.14 


1940.00 


37.8 


118.75 


1122.21 


43-8 


137.60 


1506 74 


49 8 


156.45 


1947.82 


37-9 


119.07 


1128.15 j 


43.9 


137.92 


1513-63 


49-9 


156.77 


1955.65 


380 


119.38 


1134.11 , 


44 


138.23 


1520.53 


50.0 


157.08 


1963.50 


38.1 


119.69 


1140.09 


44.1 


138.54 


I527.45 


51 


160.22 


2042 . 82 


38.2 


120.01 


1146.08 


44.2 


138.86 


1534-39 


52 


163.36 


2123.72 


38.3 


120.32 


1152.09 


44-3 


J 39'i7 


1541.34 


53 


166.50 


2206.19 


38.4 


120.64 


1158.12 


44.4 


139-49 


1548.30 


54 


169.64 


2290.22 


38.5 


120.95 


1164.16 


44-5 


139.80 


I555-28 


55 


172.79 


2375.83 


38.6 


121.27 


1 1 70. 21 


44.6 


140.12 


1562.28 


56 


175-93 


2463.01 


38.7 


121.58 


1176.28 


44-7 


140.43 


1569.30 


57 


179.07 


2551-76 


38.8 


121.89 


1182.37 


44-8 


140.74 


1576.33 


58 


182.21 


2642.08 


38 9 


122.21 


1188.47 


44.9 


141.06 


I583.37 


59 


185-35 


2733.97 


39 


122.52 


1*94-59 


45.0 


Mi- 37 


i59o.43 


60 


188.50 


2827.44 


39-i 


122.84 


1200.72 


45-i 


141.69 


I597-5I 


61 


191.64 


2922.47 


39-2 


123.15 


1206.87 


45-2 


142.00 


1 604 . 60 


62 


194.78 


3019.07 


39-3 


123.46 


1213.04 


45-3 


142.31 


1611.71 


63 


197.92 


3117.25 


39-4 


123.78 


1219.22 


45-4 


142.63 


1618.83 


64 


201.06 


3216.99 


39-5 


124.09 


1225.42 


45-5 


142.94 


1625.97 


65 


204 . 20 


3318.31 


39<6 


124.41 


1231.63 


45-6 


143.26 


1633.13 


66 


207.34 


3421.19 


39-7 


124.72 


1237.86 


45-7 


x 43-57 


1640.30 


67 


210.49 


3525.65 


39-8 


125.04 


1244.10 


45-8 


143 88 


1647.48 


68 


213.63 


3631-68 


39-9 


125.35 


1250.36 


45-9 


144.20 


1654.68 


69 


216.77 


3739-28 


40 O 


125.66 


1256.64 


46 O 


I 44-5i 


1661 .90 


70 


219.91 


3848.45 


40. 1 


125.98 


1262.93 


46.1 


144.83 


1669.14 


71 


223.05 


3959.19 


40.2 


126.29 


1269.23 j 


46.2 


145.14 


1676.39 


72 


226.19 


4071.50 


4o-3 


126.61 


1275.56 j 


46.3 


145.46 


1683.65 


73 


229.34 


4185-39 


40.4 


126.92 


1281.90 


46.4 


M5-77 


1690.93 


74 


232.48 


4300.84 


40-5 


127.23 


1288.25 


46.5 


146.08 


1698.23 


75 


235.62 


4417.86 


40.6 


127.55 


1294.62 


46.6 


146 40 


170504 


76 


238.76 


4536.46 


40.7 


127.86 


1301.00 


46.7 


146.71 


1712.87 


77 


241.90 


4656.63 


40.8 


128.18 


1307-41 


46.8 


M7.03 


1720.21 


78 


245.04 


4778.36 


40.9 


128.49 


1313.82 


46.9 


M7-34 


1727.57 


79 


248.19 


490 t .67 


41.-O 


128.81 


1320.25 


47 


M7-65 


1 734 -94 


80 


251.33 


5026.55 


41. 1 


129.12 


1326.70 


47.1 


M7-97 


1742.34 


81 | 


254.47 


5153-00 



260 ENGINEERING LABORATORY PRACTICE. 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



Diam. 



82 

83 
84 
85 
86 

87 
88 
89 
90 

91 
92 

93 

94 

95 

96 

97 

98 

99 

IOO 

101 

102 

103 

104 

105 

106 
107 
108 
109 
no 
in 
112 

"3 
114 

"5 
116 
117 
118 
119 
120 
121 
122 
123 
124 
125 
126 
127 
128 
129 
130 

131 

132 

133 
*34 
135 
136 
137 
138 

139 
140 

141 



Circum 



257.61 
260.75 
263.89 
267.04 
270.18 

273-3 2 
276.46 
279.60 
282.74 
285.88 
289.03 
292.17 

295 -3 1 
298.45 

301.59 
304.73 
307.88 
311.02 
314.16 

317.30 
320.44 

323-58 
326.73 
329.87 
333-OI 
336.15 
339.29 
342.43 
345.58 
348.72 
351.86 
355- 00 

358.14 
361.28 
364.42 
367.57 
370. 7 1 
373-85 
376.99 
380.13 
383-27 
386.42 
389.56 
392.70 
395.84 
398.98 
402.12 
405.27 
408.41 

4H-55 

414.69 

417-83 
420.97 
424.12 
427.26 
430.40 
433-54 
436.68 
439.82 
442.96 



Area. 


Diam. 


5281.02 


142 


5410.61 


J 43 


554*-77 


144 


5674-50 


M5 


5808.80 


146 


5944.68 


147 


6082.12 


148 


6221. 14 


149 


6361.73 


150 


6503.88 


*5 l 


6647.61 


152 


6792.91 


153 


6939.78 


154 


7088.22 


155 


7238.23 


156 


7389.81 


157 


7542.96 


158 


7697.69 


159 


7853.98 


160 


8011.85 


161 


8171.28 


162 


8332.29 


163 


8494.87 


164 


8659.01 


165 


8824.73 


166 


8992.02 


167 


9160.88 


168 


933 I -3 2 


169 


9503.32 


170 


9676.89 


171 


9852.03 


172 


10028.75 


173 


10207.03 


J 74 


T0386.89 


J75 


10568.32 


176 


10751.32 


177 


10935.88 


178 


11 122.02 


179 


1 1309- 73 


180 


11499.01 


181 


11689.87 


182 


11882.29 


183 


12076.28 


184 


12271.85 


185 


12468.98 


186 


12667.69 


187 


12867.96 


188 


1 3069. 8 1 


189 


13273.23 


190 


13478.22 


191 


13684.78 


192 


13892. 91 


193 


14102.61 


194 


14313.88 


195 


14526.72 


196 


14741.14 


197 


14957.12 


198 


15174.68 


190 


T 5393-8o 


200 


15614.50 


201 



Circum 



446.11 
449.25 
452-39 
455-53 
458.67 
461.81 
464.96 
468.10 
471.24 
474-38 
477.52 
480.66 
483.81 
486.95 
490.09 
493-23 
496.37 
499-51 
502.65 
505.80 
508.94 
512.08 
515-22 
518.36 
521.50 
524-65 
52779 
530.93 
534.07 
537-21 
540.35 
543.5o 
546.64 
549.78 
552.92 
556.06 
559- 20 
562.35 

56S-49 
568.63 

571-77 
574-91 
578.05 
581.19 

584.34 
587.48 
590.62 
593.76 
596.90 
600 . 04 
603.19 
606.33 
609.47 
612.61 

6i5.75 
618.89 
622.04 
625.18 
628.32 
631.46 



Area. 


Diam. 


15836.77 


202 


16060.61 


203 


16286.02 


204 


16513.00 


205 


16741.55 


206 


16971.67 


207 


17203.36 


208 


17436.62 


209 


17671 .46 


210 


17907.86 


211 


18145.84 


212 


18385.39 


213 


18626.50 


214 


18869.19 


215 


i9"3-45 


216 


19359.28 


217 


19606.68 


218 


19855.65 


219 


20106.19 


220 


20358. 31 


221 


20611.99 


222 


20867.24 


223 


21124.07 


224 


21382.46 


225 


21642.43 


226 


21903.97 


227 


22167.08 


228 


22431.76 


229 


22698.01 


230 


22965.83 


231 


23235.22 


232 


23506.18 


233 


23778.71 


234 


24052.82 


235 


24328.49 


236 


24605 . 74 


237 


24884.56 


238 


25164.94 


239 


25446.90 


240 


25730.43 


241 


26015.53 


242 


26302.20 


243 


26590.44 


244 


26880.25 


245 


27171.63 


246 


27464.59 


247 


27759.11 


248 


28055.21 


249 


28352.87 


250 


28652.11 


25 1 


28952.92 


252 


29255-30 


253 


29559.25 


254 


29864.77 


255 


30171.86 


256 


30480.52 


257 


30790.75 


258 


31102.55 


259 


3i4i5.93 


260 


3'73o.87 


261 



Circum. 



634.60 

637-74 
64c. 88 
644.03 
647.17 
650.31 
653-45 
656.59 
659-73 
662.88 
666.02 
669.16 
672.30 
675-44 
678.58 

681.73 
684.87 
688.01 

691.15 
694.29 

697.43 
700.58 
703 . 72 
706.86 
710.00 

7I3.H 
716.28 
719.42 
722.57 

725 -7 1 
728.85 
731.99 
735.13 
738.27 
741.42 
744-56 
747.70 
750.84 
753-98 
757-12 
760.27 
763-4* 
766.55 
769.69 
772.83 
775-97 
779-n 
782.26 
785.40 
788.54 
791.68 
794.82 
797.96 
801. 1 1 
804.25 
807.39 
810.53 
813.67 
816.81 
819.96 



Area. 



32047.39 

32365.47 
32685.13 
33006.36 
33329-16 
33653-53 
33979-47 
34306.98 
34636.06 
34966.71 
35298.94 
35632.73 
35968.09 
36305.03 

36643-54 
36983.61 
37325-26 
37668.48 
38013.27 
38359.63 
38707.56 

39057.07 
39408.14 
39760.78 
40115.00 
40470.78 
40828.14 
41187.07 
4 x 547-56 
41909.63 
42273.27 
42638.48 
43005.26 
43373-6i 
43743-54 
44115.03 
44488.09 
44862.73 

45238.93 
45616.71 
45996.06 
46376.98 
46759.47 
47H3-52 
47529.16 
47916.36 
48305.13. 
48695.47 

49087.39 
49480.87 
49875.92 
50272.55 
50670.75 
51070.52 

5r47 T -85 
51874.76 
52279.24 
52685.29 
53092.92 
53502.11 



APPENDIX. 



26l 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



Diam. 


Circum. 


Area. 


Diam. 

309 


Circum. 

97o-75 


Area. 


Diam. 


Circum. 
1115.27 


Area. 


262 


823.10 


53912.87 


74990 . 60 


355 


98979.80 


263 


826.24 


54325.21 


3io 


973-89 


75476.76 


356 


1118.41 


99538.22 


264 


829.38 


54739.11 


3" 


977.04 


75964.50 


357 


"21.55 


100098.21 


265 


832.52 


55 I 54-59 


312 


980.18 


76453.80 


358 


1124.69 


100659.77 


266 


835.66 


5557i-6i 


313 


983-32 


76944.67 


359 


1127.83 


101222.90 


267 


838.81 


55990.25 


3*4 


986.46 


77437-12 


360 


1130.97 


101787.60 


268 


841.95 


56410.44 


3*5 


989.60 


77931.13 


361 


1134.11 


102353.87 


269 


845.09 


56832.20 


316 


992.74 


78426.72 


362 


1137.26 


102921.72 


270 


848.23 


57 2 55-53 


3i7 


995-88 


78923.88 


363 


1140.40 


103491-13 


271 


851-37 


57680.43 


318 


999.03 


79422.60 


364 


"43-54 


104062.12 


272 


854.51 


58106.90 


3i9 


1002.17 


79922.90 


365 


t 146. 68 


1C4634.67 


273 


857-65 


58534-94 


320 


1005.31 


80424.77 


366 


1149.82 


105208.80 


274 


860.80 


58964-55 


321 


1008.45 


80928.21 


367 


1152.96 


105784.49 


275 


863.94 


59395-74 


322 


1011 .59 


81433.22 


368 


1156.11 


106361.76 


276 


867.08 


59828.49 


323 


1014.73 


81939.80 


36Q 


"59-25 


106940.60 


277 


870.22 


60262.82 


324 


1017.88 


82447.96 


370 


1162.39 


107521 .01 


278 


873-36 


60698.71 


325 


1021.02 


82957.68 


37i 


"65.53 


108102.99 


279 


876.50 


61136.18 


326 


1024.16 


83468.98 


372 


1168.67 


108686.54 


280 


879.65 


61575.22 


327 


1027.30 


83981.84 


373 


1171.81 


109271.66 


281 


882.79 


62015.82 


328 


1030.44 


84496.28 


374 


1174.96 


109858.35 


282 


88593 


62458.00 


329 


1033.58 


85012.28 


375 


1178.10 


110446.62 


283 


889.07 


62901.75 


330 


1036.73 


85529.86 


376 


1181.24 


111036.45 


284 


892.21 


63347.07 


33 1 


1039.87 


86049.01 


377 


1184.38 


1 1 1627. 86 


285 


895-35 


63793.97 


332 


1043.01 


86569.73 


378 


1187.52 


112220.83 


286 


898.50 


64242.43 


333 


1046.15 


87092.02 


379 


1190.66 


112815.38 


287 


901 . 64 


64692.46 


334 


1049.29 


87615.88 


380 


1193.81 


113411.49 


288 


904.78 


65144.07 


335 


1052.43 


88141.31 


381 


1196.95 


1 14009. 18 


289 


907.92 


65597.24 


336 


1055.58 


88668.31 


382 


1200.09 


114608.44 


290 


911.06 


66051.99 


337 


1058.72 


89196.88 


383 


1203.23 


115209.27 


291 


914.20 


66508 . 30 


338 


1061.86 


89727.03 


384 


1206.37 


115811.67 


292 


9I7-35 


66966.19 


339 


1065.00 


90258.74 


385 


1209.51 


116415.64 


293 


920.49 


67425.65 


340 


1068.14 


90792.03 


386 


1212.65 


117021 .18 


294 


923.63 


67886.68 


34i 


1071.28 


91326.88 


387 


1215 .80 


117628.30 


295 


926.77 


68349.28 


342 


1074.42 


91863.31 


388 


1218.94 


118236.98 


296 


929.91 


68813.45 


343 


1077.57 


92401.31 


389 


1222.08 


118847.24 


297 


933 05 


69279.19 


344 


1080.71 


92940.88 


390 


1225.22 


119459.06 


298 


936.19 


69746.50 


345 


1083.85 


93482.02 


39i 


1228.36 


120072.46 


299 


939-34 


70215.38 


346 


1086.99 


94024.73 


392 


1231.50 


120687.42 


300 


942.48 


70685.83 


347 


1090.13 


94569.01 


393 


1234-65 


121303.96 


301 


945.62 


71157.86 


348 


1093.27 


95114.86 


394 


1237.79 


121922.07 


302 


948.76 


71631.45 


349 


1096.42 


95662.28 


395 


1240.93 


122541.75 


303 


951.90 


72106.62 


350 


1099 . 56 


96211 .28 


396 


1244.07 


123163.00 


304 


955-04 


72583 36 


35* 


1102.70 


96761.84 


397 


1247.21 


123785.82 


305 


958. 19 


73061 .66 


35 2 


1105.84 


973*3-97 


398 


1250.35 


124410.21 


306 


961.33 


7354L54 


353 


1108.98 


97867.68 


399 


1253.50 


125036.17 


3°7 


964.47 


74022.99 


354 


III2.I2 


98422.96 


400 


1256 .64 


125663.71 


308 


967.61 


74506.01 








1 







262 



ENGINEERING LABORATORY PRACTICE. 







178. Decimal 


Equivalents. 




8ths and 
i6ths. 


32ds. 


6 4 ths. I 


Decimals. 


8ths and 
i6ths. 


32ds. 


64ths. 


Decimals. 






I 


015625 


9/16 


18 


36 


.5625 




I 


2 


03125 






37 


.578125 






3 


046875 




19 


38 


•59375 


I/I6 


2 


4 


0625 






39 


609375 






5 


078125 


5/8 


20 


40 


.625 




3 


6 


09375 






41 


.640625 






7 


109375 




21 


42 


.65625 


1/8 


4 


8 


125 






43 


.671875 






9 


140625 


11/16 


22 


44 


.6875 




5 


10 


15625 






45 


.703125 






11 


I7I875 




23 


46 


.71875 


3/16 


6 


12 


1875 






47 


•734375 






13 


203125 


3/4 


24 


48 


• 75 




7 


14 


21875 






49 


.765625 






15 


234375 




25 


50 


.78125 


i/4 


8 


16 


25 






5i 


.796875 






17 


265625 


13/16 


26 


52 


.8125 




9 


18 


28125 






53 


.828125 






19 


296875 




27 


54 


.84375 


5/i6 


10 


20 


3125 






55 


.859375 






21 


328125 


7/8 


28 


56 


.875 




11 


22 


34375 






57 


.890625 






23 


359375 




29 


58 


.90625 


3/8 


12 


24 


375 






59 


.92 875 






25 


390625 


15/16 


30 


60 


•9375 




13 


26 


40625 






61 


•953125 






27 


421875 




31 


62 


.96875 


7/16 


14 


28 


4375 






63 


.984375 






29 


453125 


1 


32 


64 


1. 00 




15 


30 
3i 


46875 
484375 










1/2 


16 
17 


32 
33 
34 
35 


5 

515625 

53125 

.546875 











APPENDIX. 



263 



179. Weights of Various Materials. 



Material. 



Cast iron 

Wrought iron . 

Soft steel 

Hard steel 

Brass 

Lead 

Copper — cast. . 
Copper — sheet. 

Mercury 

Zinc 

Tin 

Timber 

Stone 

Brick 

Mortar 

Water 



Approx 
Sp. Gravity, 



•4 
2.2 
1.6 



7-1 

7-7 
7.9 
7.7 

8.4' 
14 

8-7 
8.9 
3.6 

7-1 

7 3 
to .8 
to 2 8 
to 2.1 

1-5 

1 



Pounds per 
Cubic Inch. 



.2607 

.281 

.285 

.278 

.304 

.410 

.315 
.322 

.490 

•253 

.263 
.0144 to .0289 
.079 to .101 
0578 to .0752 

.0544 

.036 



Pounds per 
Cubic Foot. 



450 

486 

493 
480 

525 
709 

543 

555 

847 

437 

458 

25 to 50 

137 to 175 

100 to 130 

94 
62.4 



Cubic Feet 
per Ton (2000). 



4.44 
4.II 
4.06 

4 17 
3.81 
2.82 
3.68 
3.60 
2.36 
4.58 

4-37 

80 to 40 

14.6 to 11 4 

20 to 15.4 

21.3 

32.0 



264 ENGINEERING LABORATORY PRACTICE. 

180. Weight of Water. 



Tempera- 


Weight per 


Tempera- 


Weight per 


Tempera- 


Weight per 


ture. 


Cubic Foot. 


ture. 


Cubic Foot. 


ture. 


Cubic Foot. 


Fahr. 


Pounds. 


Fahr. 


Pounds. 


Fahr. 


Pounds. 


32 


62.42 


122 


61.70 


168 


60.81 


40 


62.42 


124 


61.67 


170 


60.77 


45 


62.42 


120 


61.63 


172 


60.73 


5o 


62.41 


128 


61.60 


174 


60.68 


55 


62.39 


130 


61.56 


176 


60.64 


60 


62.37 


132 


61.52 


178 


60.59 


65 


62.34 


134 


61.49 


180 


60.55 


70 


62.31 


136 


61.45 


182 


60.50 


75 


62.27 


138 


61.41 


184 


60.46 


80 


62.23 


140 


61.37 


186 


60.41 


85 


62.18 


142 


61.34 


188 


60.37 


90 


62.13 


144 


61.30 


190 


60.32 


95 


62.04 


146 


61.26 


192 


60.27 


100 


62.02 


148 


61.22 


194 


6o.22 


102 


62.OO 


I50 


61.18 


196 


60.17 


104 


61.97 


152 


61.14 


198 


60.12 


106 


61.95 


154 


61.IO 


200 


60.07 


108 


61.92 


156 


61.06 


202 


60.02 


no 


61.89 


158 


61.02 


204 


59.97 


112 


61.86 


160 


60.98 


206 


59.92 


114 


61.83 


l62 


60.94 


208 


59.87 


116 


61.80 


164 


60.90 


2IO 


59.82 


118 


61.77 


166 


60.85 


212 


59-76 


120 


61.74 











COMPARISON OF HEADS. 



One foot of water at 50 F. = 62.41 pounds per sq. ft. 



One foot of water at 50 F. 
One foot of water at 50 F. 
One pound per sq. ft. at 50 F. 
One pound per sq. in. at 50 F. 
One inch of mercury at 32 F. 
One atmosphere of 29.92 in, of mer. 



0.4334 pounds P er s q« in- 
0.8845 in. mercury at 32 F. 
0.01602 feet of water. 
2.308 feet of water. 
1. 130 feet of water. 
33.80 feet of water. 



APPENDIX. 265 

181. Melting-points of Metals. 

Mercury — 38 F. 

Tin 442 F. 

Bismuth 497 F. 

Lead 612 F. 

Zinc 773 F. 

Antimony 8io° F. 

Brass 1869 F. 

Silver 1874 F. 

Copper 1995° F. 

Gold 2016 F. 

Iron, cast 2780 F. 

Platinum 3280 F. 



266 



ENGINEERING LABORATORY PRACTICE. 



182. 



Properties of Saturated Steam. 

(Abridged from Kent.) 



Vacuum- 
gage. 
Inches of 
Mercury. 


Absolute 

Pressure. 

Lbs. per 

Sq. In. 


Tempera- 
ture. 
Fahrenheit. 


Heat of the 
Liquid. 


Heat of 
Vaporiza- 
tion. 
r. 


Weight of 1 

Cu. Ft. in 

Pounds. 


29.74 


.089 


32 


O 


IO9I.7 


.OOO30 


29.67 


.122 


40 


. 8 


I086. I 


.00040 


29.56 


.176 


50 


18 


IO79.2 


.OOO58 


29.40 


•254 


60 


28.01 


1072.2 


.OOO82 


29.19 


•359 


70 


38.02 


IO65.3 


.OOII5 


28.90 


.502 . 


80 


48.04 


1058.3 


.OOI58 


28.51 


.692 


90 


58.06 


I05L3 


.OO213 


28.OO 


•943 


IOO 


68.08 


IO44.4 


.00286 


27.88 


I 


I02. 1 


70.09 


IO43.O 


.OO299 


25.85 


2 


126.3 


94.44 


1026.0 


.OO577 


23.83 


3 


141. 6 


109.9 


IOI5.3 


.00848 


21.78 


4 


I53.I 


121. 4 


IOO7.2 


.OIII2 


19.74 


5 


162.3 


130.7 


IOOO.7 


.OI372 


17.70 


6 


170. 1 


138.6 


995.2 


.01631 


15.67 


7 


176.9 


145.4 


990.5 


.01887 


13.63 


8 


182.9 


155.5 


986.2 


.02140 


II.60 


9 


188.3 


156.9 


982.4 


.02391 


9.56 


10 


193.2 


161. 9 


979.O 


.02641 


7.52 


11 


197.8 


166.5 


975.8 


.02889 


5.49 


12 


202.0 


170.7 


972.8 


.03136 


3-45 


13 


205.9 


174.7 


970.O 


.03381 


1. 41 


14 


209.6 


178.4 


967.4 


.03625 


Gage-pres- 
sure. Lbs. 


14.7 


212.0 


180.9 


965.7 


.03794 


per Sq. In. 












O.304 


15 


213.0 


181. 9 


905.0 


.03868 


1-3 


16 


216.3 


185.3 


962.7 


.O4IIO 


2.3 


17 


219.4 


188.4 


960.5 


.04352 


3.3 


18 


222.4 


I9I-4 


958.3 


.04592 


4-3 


19 


225.2 


194-3 


956.3 


.04831 


5.3 


20 


227.9 


197.0 


954-4 


.05070 


6.3 


21 


230.5 


199.7 


952.6 


.05308 


7-3 


22 


233-o 


202.2 


950.8 


.05545 


8.3 


23 


235.4 


204.7 


949.1 


.05782 


9-3 


24 


237.8 


207.0 


947-4 


.06018 



APPENDIX. 
PROPERTIES OF SATURATED STEAM. 



26j 



Gage- 
pressure. 
Lbs. per 
Sq. In. 


Absolute 

Pressure. 

Lbs. per 

Sq. In. 


Tempera- 
ture. 
Fahrenheit. 


Heat of the 
Liquid. 


Heat of 
Vaporiza- 
tion. 
r. 


Weight of 1 

Cu. Ft. in 

Pounds. 


IO.3 


25 


240.O 


209.3 


945-8 


.06252 


H-3 


26 


242.2 


211. 5 


944.3 


.06487 


12.3 


27 


244-3 


213.7 


942.8 


.06721 


13.3 


28 


246.3 


215.7 


941.3 


.06955 


14.3 


29 


248.3 


217.8 


939-9 


.07188 


15.3 


30 


250.2 


219.7 


938.9 


.07420 


16.3 


31 


252.1 


221.6 


937-2 


.07652 


17-3 


32 


254.0 


223.5 


935-9 


.07884 


18.3 


33 


255.7 


225.3 


934.6 


.08115 


19.3 


34 


257.5 


227.1 


933-4 


.08346 


20.3 


35 


259.2 


228.8 


932.2 


.08576 


21.3 


36 


260.8 


23O.5 


93I.O 


.08806 


22.3 


37 


262.5 


232.1 


929.8 


.09035 


23.3 


38 


264.0 


233.8 


928.7 


.09264 


24.3 


39 


265.6 


235.4 


927.6 


.09493 


25.3 


40 


267.1 


236.9 


926.5 


.09721 


26.3 


41 


268.6 


238.5 


925.4 


•09949 


27.3 


42 


270.1 


24O.O 


924.4 


.IOI8 


28.3 


43 


271.5 


24I.4 


923.3 


.IO40 


29.3 


44 


272.9 


242.9 


922.3 


.1063 


30.3 


45 


274-3 


244.3 


921.3 


.IO86 


3i-3 


46 


275.7 


245.7 


920.4 


.1108 


32.3 


47 


277.0 


247.O 


919.4 


.1131 


33-3 


48 


278.3 


248.4 


918.5 


•1153 


34-3 


49 


279.6 


249.7 


917.5 


.1176 


35-3 


50 


280.9 


25I.O 


916.6 


.II98 


36.3 


5i 


282.1 


252.2 


915.7 


.1221 


37-3 


52 


283.3 


253.5 


914.9 


.1243 


38.3 


53 


284.5 


254.7 


914 O 


.1266 


39-3 


54 


285.7 


256.O 


913. 1 


.1288 


40.3 


55 


286.9 


257.2 


912.3 


.1311 


41.3 


56 


288.1 


258.3 


9*1-5 


.1333 


42.3 


57 


289.1 


259.5 


910.6 


.1355 


43-3 


58 


290.3 


260.7 


909.8 


.1377 


44-3 


59 


291.4 


261.8 


909.0 


.I4OO 


45-3 


60 


292.5 


262.9 


908.2 


.1422 



268 



ENGINEERING LABORATORY PRACTICE. 



PROPERTIES OF SATURATED STEAM 



Gage- 
pressure. 
Lbs. per 

Sq. In. 


Absolute 

Pressure. 

Lbs. per 

Sq. In. 


Tempera- 
ture. 
Fahrenheit. 


Heat of the 
Liquid. 


Heat of 
Vaporiza- 
tion. 
r. 


Weight of 1 

Cu. Ft. in 

Pounds. 


46.3 


6l 


293.6 


264.0 


907.5 


.1444 


47.3 


62 


294.7 


265.1 


906.7 


.1466 


48.3 


63 


295.7 


266.2 


905.9 


.1488 


49-3 


64 


296.8 


267.2 


905.2 


.1511 


50.3 


65 


297.8 


268.3 


904.5 


.1533 


51.3 


66 


298.8 


269.3 


903.7 


.1555 


52.3 


67 


299.8 


270.4 


903.O 


•1577 


53-3 


68 


300.8 


271.4 


902.3 


.1599 


54-3 


69 


301.8 


272.4 


9OI.6 


.1621 


55-3 


70 


302.7 


273.4 


9OO.9 


.1643 


56.3 


71 


303.7 


274.4 


900.2 


-1665 


57.3 


72 


304.6 


275.3 


899.5 


.1687 


58.3 


73 


305.6 


276.3 


898.9 


.1709 


59-3 


74 


306.5 


277.2 


898.2 


.1731 


60.3 


75 


307.4 


278.2 


897.5 


.1753 


61.3 


76 


308.3 


279- 1 


896.9 


.1775 


62.3 


77 


309.2 


280.0 


896.2 


•1797 


63-3 


78 


310.1 


280.9 


895.6 


.1819 


64.3 


79 


310.9 


281.8 


895.O 


.1840 


65.3 


80 


311. 8 


282.7 


894.3 


.1862 


66.3 


81 


312.7 


283.6 


893.7 


.1884 


67.3 


82 


313.5 


284.5 


893.I 


.1906 


68.3 


83 


314.4 


285.3 


892.5 


.1928 


69.3 


84 


315.2 


286.2 


89I.9 


.1950 


70.3 


85 


316.0 


287.0 


89I.3 


.1971 


71.3 


86 


316.8 


287.9 


890.7 


.1993 


72.3 


87 


317.7 


288.7 


89O.I 


.2015 


73-3 


88 


3i8.5 


289.5 


889.5 


.2036 


74-3 


89 


319.3 


290.4 


888.9 


.2058 


75.3 


90 


320.0 


291.2 


888.4 


.2080 


76.3 


*9i 


320.8 


292.0 


887.8 


.2102 


77.3 


92 


321.6 


292.8 


887.2 


.2123 


78.3 


93 


322.4 


293.6 


886.7 


.2145 


79-3 


94 


323.1 


294.4 


886.1 


.2166 


80.3 


95 


323.9 


295.1 


885.6 


.2188 


81.3 


96 


324.6 


295.9 


885.0 


.22IO 



APPENDIX. 
PROPERTIES OF SATURATED STEAM. 



269 



Gage- 
pressure. 
Lbs. per 

Sq. In. 


Absolute 

Pressure. 

Lbs. per 

Sq. In. 


Tempera- 
ture. 
Fahrenheit. 


Heat of the 
Liquid. 


Heat of 
Vaporiza- 
tion. 
r. 


Weight of 1 
Cu. Ft. in 

Pounds. 


82.3 


97 


325.4 


296.7 


884.5 


.2231 


83.3 


98 


326.1 


297.4 


884.O 


.2253 


84.3 


99 


326.8 


298.2 


883.4 


.2274 


85.3 


100 


327.6 


298.9 


882.9 


.2296 


86.3 


IOI 


328.3 


299.7 


882.4 


.2317 


87.3 


102 


329.O 


300.4 


881.9 


.2339 


88.3 


103 


329.7 


301. 1 


881.4 


.2360 


89.3 


104 


330.4 


30I.9 


880.8 


.2382 


90.3 


105 


33I-I 


302.6 


880.3 


.2403 


91-3 


106 


331.8. 


303.3 


879.8 


.2425 


92.3 


107 


332.5 


304.O 


879.3 


.2446 


93.3 


108 


333-2 


304.7 


878.8 


.2467 


94-3 


109 


333-9 


305.4 


878.3 


.2489 


95.3 


no 


334-5 


306.I 


877.9 


.2510 


96.3 


III 


335.2 


306.8 


877.4 


.2531 


97.3 


112 


335-9 


307.5 


876.9 


.2553 


98.3 


113 


336.5 


308.2 


876.4 


.2574 


99-3 


114 


337.2 


308.8 


875.9 


.2596 


100.3 


115 


337-8 


309.5 


875.5 


.2617 


101.3 


Il6 


338.5 


310.2 


875.0 


.2638 


102.3 


117 


339-1 


3I0.8 


874.5 


.2660 


103.3 


Il8 


339-7 


311. 5 


874.1 


.2681 


104.3 


119 


340.4 


312. 1 


873.6 


.2703 


105.3 


I20 


341-0 


312.8 


873.2 


.2724 


106.3 


121 


341.6 


3I3.4 


872.7 


.2745 


107.3 


122 


342.2 


314.1 


872.3 


.2766 


108.3 


123 


342.9 


3I4.7 


87I.8 


.2788 


109.3 


124 


343-5 


315.3 


871.4 


.2809 


1 10. 3 


125 


344-1 


316.0 


870.9 


.2830 


in- 3 j 


126 


344.7 


316.6 


870.5 


.2851 


112.3 


127 


345-3 


317.2 


87O.O 


.2872 


113. 3 


128 


345-9 


317.8 


869.6 


.2894 


II4-3 


129 


346.5 


318.4 


869.2 


.2915 


115.3 


I30 


347.1 


319-1 


868.7 


.2936 


116.3 


131 


347-6 


319.7 


868.3 


.2957 


117. 3 


132 


348.2 


320.3 


867.9 


.2978 



270 



ENGINEERING LABORATORY PRACTICE, 



PROPERTIES OF SATURATED STEAM. 



Gage- 
pressure. 
Lbs. per 

Sq. In. 


Absolute 

Pressure. 

Lbs. per 

Sq. In. 


Tempera- 
ture. 
Fahrenheit. 


Heat of the 
Liquid. 


Heat of 
Vaporiza- 
tion. 
r. 


Weight of 1 

Cu. Ft. in 

Pounds. 


118. 3 


133 


348.8 


320.8 


867.5 


.3000 


"9-3 


134 


349-4 


321.5 


867.O 


.3021 


120.3 


135 


350.0 


322.1 


866.6 


.3042 


121. 3 


136 


350.5 


322.6 


866.2 


.3063 


122.3 


137 


351. 1 


323.2 


865.8 


.3084 


123.3 


138 


351.8 


323.8 


865.4 


.3105 


124.3 


139 


352.2 


324-4 


865.0 


.3126 


125.3 


140 


352-8 


325.0 


864.6 


.3147 


126.3 


141 


353-3 


325.5 


864.2 


.3169 


127.3 


142 


353-9 


326.1 


863.8 


.3190 


128.3 


143 


354-4 


326.7 


863.4 


.3211 


129.3 


144 


355-o 


327.2 


863.0 


.3232 


130.3 


145 


355-5 


327.8 


862.6 


.3253 


I3I-3 


146 


356.o 


328.4 


862.2 


.3274 


1323 


147 


356.6 


328.9 


861.8 


.3295 


133-3 


148 


357-1 


329.5 


861.4 


.3316 


134-3 


149 


357-6 


330.0 


861.0 


•3337 


135.3 


150 


358.2 


330.6 


860.6 


.3358 


136.3 


151 


358.7 


331-1 


860.2 


•3379 


137-3 


152 


359-2 


331.6 


859-9 


.3400 


138.3 


153 


359-7 


332 2 


859-5 


.3421 


139-3 


154 


360.2 


332.7 


859.1 


-3442 


140.3 


155 


360.7 


333-2 


858.7 


.3463 


141. 3 


156 


361.3 


333.8 


858.4 


.3483 


142.3 


157 


361.8 


334-3 


858.0 


.3504 


143-3 


158 


362.3 


334.8 


857.6 


•3525 


144-3 


159 


362.8 


335.3 


857.2 


.3546 


145-3 


160 


363-3 


335-9 


856.9 


.3567 


146.3 


161 


363.8 


336.4 


856.5 


.3588 


147-3 


162 


364.3 


336.9 


856.1 


.3609 


148.3 


163 


364.8 


337-4 


855-8 


.3630 


149-3 


164 


365-3 


337-9 


855.4 


.3650 


150.3 


165 


365.7 


338.4 


855.1 


.3671 


151. 3 


166 


366.2 


338.9 


854.7 


.3692 


152.3 


167 


366.7 


339-4 


854.4 


.3713 


153.3 


168 


367.2 


339-9 


854.0 


•3734 


154-3 


169 


367.7 


340.4 


853.6 


•3754 



APPENDIX. 
PROPERTIES OF SATURATED STEAM. 



27I 



Gage- 

pressure. 

Lbs. per 

Sq. In. 


Absolute 

Pressure. 

Lbs. per 

Sq. In. 


Tempera- 
ture. 
Fahrenheit. 


Heat of the 

Liquid. 

9- 


Heat of 
Vaporiza- 
tion. 
r. 


Weight of 1 

Cu. Ft. in 

Pounds. 


155.3 


170 


368.2 


340.9 


853.3 


•3775 


156.3 


171 


368.6 


341-4 


852.9 


.3796 


157.3 


172 


369.I 


341.9 


852.6 


o8l7 


158.3 


173 


369.6 


342.4 


852.3 


.3838 


159-3 


174 


370.0 


342.9 


851.9 


.3858 


160.3 


175 


370.5 


343-4 


851.6 


.3879 


l6l. 3 


176 


37I.O 


343-9 


851.2 


.3900 


162.3 


177 


371-4 


344-3 


850.9 


.3921 


163.3 


178 


371-9 


344-8 


850.5 


•3942 


164.3 


179 


372.4 


345-3 


850.2 


.3962 


165.3 


180 


372.8 


345.8 


849.9 


.3983 


166.3 


181 


373-3 


346.3 


849.5 


.4004 


167.3 


182 


373-7 


346.7 


849.2 


•4025 


168.3 


183 


374-2 


347-2 


848.9 


.4046 


169.3 


184 


374-6 


347.7 


848.5 


.4066 


170.3 


185 


375-1 


348.1 


848.2 


.4087 


171. 3 


186 


375-5 


348.6 


847.9 


.4108 


172.3 


1S7 


375-9 


349.1 


847.6 


.4129 


173-3 


188 


376.4 


349-5 


847.2 


.4150 


174-3 


189 


376.9 


35o.o 


846.9 


.4170 


175.3 


190 


377.3 


350.4 


846.6 


.4191 


176.3 


191 


377-7 


350.9 


846.3 


.4212 


177-3 


192 


378.2 


351-3 


845.9 


•4233 


178.3 


193 


378.6 


351.8 


845.6 


.4254 


179-3 


194 


379 


352.2 


845.3 


.4275 


180.3 


195 


379-5 


352.7 


845.O 


.4296 


181. 3 


196 


380.0 


353-1 


844.7 


.4317 


182.3 


197 


380.3 


353-6 


844.4 


•4337 


183.3 


198 


3807 


354-0 


844.I 


.4358 


184.3 


199 


381.2 


354-4 


843.7 


•4379 


185.3 


200 


381.6 


354-9 


843.4 


.4400 


186.3 


201 


382.0 


355-3 


843.I 


.4420 


187.3 


202 


382.4 


355-8 


842.8 


.4441 


188.3 


203 


382.8 


356.2 


842.5 


.4462 


189.3 


204 


383.2 


356.6 


842.2 


.4482 


190.3 


205 


383.7 


357-1 


841.9 


.4503 



272 ENGINEERING LABORATORY PRACTICE, 

PROPERTIES OF SATURATED STEAM. 



Gage- 
pressure. 
Lbs. per 

Sq. In. 


Absolute 

Pressure. 

Lbs. per 

Sq. In. 


Tempera- 
ture. 
Fahrenheit. 


Heat of the 
Liquid. 


Heat of 
Vaporiza- 
tion. 
r. 


Weight of 1 
Cu. Ft. in 
Pounds. 


191. 3 


206 


384.I 


357-5 


84I.6 


.4523 


192.3 


207 


384.5 


357.9 


841.3 


•4544 


193-3 


208 


384.9 


358.3 


84I.O 


.4564 


194.3 


209 


385.3 


358.8 


84O.7 


.4585 


195.3 


2IO 


385.7 


359-2 


84O.4 


.4605 


196.3 


211 


386.1 


359.6 


840.I 


.4626 


197.3 


212 


386.5 


360.O 


839-8 


.4646 


198.3 


213 


386.9 


360.4 


839.5 


.4667 


199.3 


214 


387.3 


360.9 


8392 


.4687 


200.3 


215 


387.7 


361.3 


838.9 


.4707 


201.3 


2l6 


388.1 


361.7 


838.6 


.4728 


202.3 


217 


388.5 


362.1 


838.3 


.4748 


203.3 


218 


388.9 


362.5 


838.I 


.4768 


204.3 


219 


389.3 


362.9 


837.8 


.4788 


205.3 


220 


389.7 


363-2 


837.6 


.4808 



APPENDIX. 



273 



183. Comparison of Fahrenheit and Centigrade 
Thermometer Scales. 



u 


+j 


u 


j 


u 


^j 


u 


^j 


In 


• 


u 


^j 


A 


c 


•fi 


a 


J3 


c 




c 


.C 


c 


-C 


c ' 


tt 


V 


rt 


V 


a 


V 


"r5 


<U 


a 


<u 


rt 


<u 


fe 


V 


fe 


V 


fc 


U 


83 


U 
28.3 


fc 


U 


fc 


U 


212 


100.0 


169 


76.I 


126 


52.2 


40 


4.4 


- 3 


-I9.4 


211 


99.4 


168 


75-5 


125 


51.6 


82 


27.7 


39 


3-8 


- 4 


— 20.0 


2IO 


98.8 


I167 


75.0 


124 


51. 1 


81 


27.2 


33 


3-3 


- 5 


— 20.5 


209 


98.3 


166 


74.4 


123 


50.5 


80 


26.6 


37 


2.7 


- 6 


— 21. I 


208 


97.7 


165 


73-3 


122 


50.0 


79 


26.1 


36 


2.2 


- 7 


— 21.6 


207 


97.2 


164 


73-3 


121 


49.4 


78 


25.5 


35 


1.6 


- 8 


— 22.2 


206 


96.6 


163 


72.7 


I20 


48.8 


77 


25.O 


34 


I.I 


— 9 


— 22.7 


205 


96.1 


162 


72.2 


119 


48.3 


76 


24.4 


33 


O.5 


— 10 


-23.3 


204 


95.5 


161 


71.6 


Il8 


47-7 


75 


23.8 


32 


O.O 


— 11 


-23.8 


203 


95.0 


160 


71. 1 


IT7 


47.2 


74 


23.3 


3i 


- O.5 


— 12 


-24.4 


202 


94-4 


159 


70.5 


Il6 


46.6 


73 


22.7 


30 


— I.I 


-13 


— 25.O 


20I 


93-3 


158 


70.0 


115 


46.I 


72 


22.2 


29 


- 1.6 


-14 


-25-5 


200 


93-3 


157 


69.4 


114 


45-5 


71 


21.6 


28 


— 2.2 


-15 


— 26.1 


199 


92.7 


156 


68.8 


113 


45-0 


70 


21. 1 


27 


- 2.7 


-16 


-26.6 


I98 


92.2 


155 


68.3 


112 


44.4 


69 


2C5 


26 


- 3.3 


-17 


— 27.2 


197 


91.6 


154 


67.7 


III 


43-8 


68 


20.0 


25 


- 3.8 


-18 


-27.7 


I96 


91. 1 


153 


67.2 


no 


43-3 


67 


I9.4 


24 


- 4.4 


-19 


-28.3 


195 


90.5 


152 


66.6 


IO9 


42.7 


66 


18.8 


23 


- 5.o 


— 20 


-28.8 


194 


90.0 


151 


66.1 


TO8 


42.2 


65 


18.3 


22 


- 5-5 


— 21 


-29.4 


193 


89.4 


150 


65.5 


107 


41.6 


64 


17-7 


21 


- 6.1 


— 22 


— 30.0 


192 


88.8 


149 


65.0 


I06 


41.1 


63 


17.2 


20 


- 6.6 


-23 


-30.5 


191 


88.3 


148 


64.4 


I05 


40.5 


62 


16.6 


19 


- 7-2 


-24 


-31. 1 


I90 


87.7 


147 


63.8 


IO4 


40.0 


61 


16. 1 


18 


- 7-7 


-25 —31.6 


189 


87.2 


146 


63.3 


IO3 


39-4 


i6o 


15-5 


17 


- 8.3 


-26 


-32.2 


188 


86.6 


145 


62.7 


I02 


38.8 


59 


15.0 


16 


- 8.8 


-27 


-32.7 


187 


86.1 


144 


62.2 


101 


38.3 


58 


14.4 


15 


- 9-4 


-28 


-33-3 


186 


85.5 


143 


61.6 


100 


37-7 


57 


13.8 


14 


— 10.0 


-29 


-33-8 


185 


85.0 


142 


61. 1 


99 


37-2 


56 


13.3 


13 


-10.5 


-30 


-34-4 


184 


84.4 


141 


60.5 


98 


36.6 


55 


12.7 


12 


— 11. 1 






183 


83.8 


140 


60.0 


97 


36.1 


54 


12.2 


11 


-11. 6 






182 


83.3 


139 


59-4 


96 


35.5 


53 


11. 6 


10 


— 12.2 






l8l 


82.7 


138 


58.8 


95 


35-0 


52 


11. 1 


9 


-12.7 






l8o 


82.2 


137 


58.3 


94 


34-4 


5i 


10.5 


8 


-13.3 






179 


81.6 


136 


57-7 


93 


33-8 


50 


10.0 


7 


-13.8 






178 


81. 1 


135 


57.2 


92 


33-3 


49 


9.4 


6 


-14.4 






177 


80.5 


134 


56.6 


9i 


32.7 


48 


8.8 


5 


-15.0 






176 


80.0 


133 


56.1 


90 


32.2 


47 


8.3 


4 


-15-5 






175 


79-4 


132 


55-5 


89 


31.6 


46 


7-7 


3 


- 16. 1 






174 


78.8 


131 


55.0 


88 


3i. 1 


45 


7-2 


2 


-16.6 






173 


78.3 


130 


54.4 


87 


30.5 


44 


6.6 


1 


— 17.2 






172 


77-7 


129 


53-8 


86 


30.0 


43 


6.1 





-17.7 






171 


77.2 


128 


53-3 


85 


29.4 


42 


5-5 


— 1 


-18.3 






I70 


76.6 


127 


52.7 


84 


28.8 


4i 

1 


5-o 


— 2 


-18.8 







274 ENGINEERING LABORATORY PRACTICE* 

184. Moments of Inertia. 



Section. 


Dimensions. 


Axis. 


Moment of Inertia. 


Rectangle... 


b X h 


On side b 


bh z 
3 


Rectangle.. . 


b X h 


Through c. of g., 
parallel to b 


bh z 
12 


Hollow j 
rectangle ( 


Outside, b X A, 
inside, b x X h\ 


Through c. of g., 
parallel to b 


bh z - b x k x z 
12 


Triangle.. •] 


Base b, 
alt. h 


Through c. of g., 
parallel to b 


bk* 
36 


Circle 


d 


Through center 


Ttd* 

"67 


Hollow ( 
circle ( 


Outside d y 
inside d\ 


Through center 


7t(d* - d^) 
64 



185. Tractive Force. — The following table gives 
the tractive force necessary to draw one ton at various 
speeds under average conditions of railway service: 



Speed. 


Tractive Force 


Miles per Hour. 


pet 


• Ton. 


15 


5.8 pounds 


25 


8.3 


i i 


35 


10.8 


i i 


45 


13-3 


i i 



APPENDIX. 



275 



186. Coefficients of Discharge of Rectangular 
Overfall Weirs with Full Contraction. 





Breadth of Weir in Feet. 




Effects 
in I 


/e Head 










r eet. 












1 


2 


3 


4 


.1 


639 


646 


•653 


.654 




15 


625 


634 


•639 


.641 




2 


618 


626 


.63I 


.632 




25 


6l2 


621 


.625 


.627 




3 


608 


616 


.620 


.622 




4 


601 


609 


.614 


.616 




5 


593 


605 


.6lO 


.613 




6 


590 


601 


.607 


.6lO 




7 


587 


598 


.605 


.608 




.8 


... 


595 


.602 


.606 




9 




5Q2 


.60O 


.605 


I.O 




590 


.598 


.604 



INDEX. 



A 

PAGE 

Absorption-dynamometers 55 

Adjustable planimeter, the. 13 

Advanced work in air-compressor testing 245 

centrifugal-pump testing 229 

impulse-wheel testing 235 

injector-testing 252 

steam-engine testing 188 

steam-pump testing - 226 

turbine-testing 231 

Air-compressors, tests of 238 

, advanced work on 245 

Air, formulae for flow of 29 

Analysis of flue-gases 125 

Anemometers for determining flow of gases 32 

Appendix 257 

Autographic recording apparatus 91 

records 104 

Areas of circles, circumferences and, table 257 

, measurement of 6 

A. S. M. E. standard method of testing boilers 126 

locomotives 193 

B 

Band-brake 58 

Barrel calorimeter, the. 52 

Belt slippage 67 

testing 65 

277 



278 INDEX. 

PAGE 

Belt transmission-dynamometer 58 

Boiler-testing 123 

, abbreviated directions for 137 

, form for 1 34 

, graphical logs for 126 

, methods of 126 

Boiler tests under different conditions 123 

Boilers, efficiency of 124 

, horse-power of , 124 

Bourdon gage, the , 33 

Boyer railway speed-recorder, the. . 5 

Brake, band 58 

y P^e 57 

> Prony 55 

Brick, rattler test for paving 1.16. 

Bristol recording pressure-gage, the 39 

C 

Calculations from the indicator-card, clearance. . o « 160 

, exercise. 163 

, horse-power 157 

, reevaporation , ... 159 

, weight of steam 158 

Calibration of gages, method by comparison with gage-tester 36 

, method by comparison with standard 34 

, form for 35 

an orifice . 24 

, form for 25 

thermometers, method by comp. with standard.... 41 
, method by comp. with steam-pres- 
sure 42 

, form for 42 

water-meters 27 

, form for 28 

Caliper, the micrometer 16 

, the vernier 16 

Calorimeters, coal 124 

, steam, barrel 52 

, Carpenter separating, 51 



INDEX. 579 

PAGE 

Calorimeters, steam, Carpenter separating, use of 52 

, exercise with 54 

, Peabody throttling 47 

, form for 51 

, limitations of 49 

, use of 50 

Card, the indicator 150 

Care of apparatus 2 

the steam-engine . . .. 175 

Carpenter separating calorimeter 51 

Cement-testing in 

machine, Olsen 88 

Centrifugal pumps, tests of . . . , , 227 

Choice of indicator-springs 144 

Circumferences and areas of circles, table. . . - 257 

Clearance from the indicator-card 160 

of the steam-engine, method of measuring 186 

Coefficient of discharge through a nozzle 25 

an orifice 22 

of rectangular weirs, table 275 

Cold-bending tests of materials 121 

Combined engine and boiler, test of 218 

Combining indicator-cards , • 161 

Commercial efficiency of the steam-engine 181 

Commonplace-book 2 

Comparison of heads of water, table. 264 

F. and C. thermometer-scales, table 273 

Compound engines, equalizing the work of 191 

, tests of 189 

Compressional tests of materials 104 

, long specimens 106 

, short specimens 104 

Compressors, tests of air 238 

Concrete, tests of » 113 

Constant, the engine 158 

Copper ball pyrometer, the 45 

Correction of gages 37 

Crosby indicator, the 139 

Cross bending tests of materials 109 

Cylinder losses of the steam engine , <, . . . 184 



280 INDEX. 

D 

PAGE 

Decimal equivalents, table 262 

Deflectometer 93 

De Laval steam-turbine, the 253 

Detroit lubricator, the 178 

Diagram, the indicator (see Indicator card). 

Diagrams, autographic 104 

, stress-strain 102 

Directions for use of the planimeter 15 

Drifting tests of materials 122 

Dynamometers, absorption 55 

, Emery locomotive 87 

, transmission 58 

E 

Efficiency of boilers 124 

the furnace 1 24 

hoists 63 

screws 60 

the steam-engine, commercial 181 

Elasticity, modulus of, definition of 95 

Elastic limit, definition of c . 94 

, determination of „ 100 

Elongation, equivalent 99 

, per cent of, definition of 96 

Emery hydraulic testing-machine 77 

locomotive dynamometer 87 

Engine and boiler, test of combined 218 

, gas, tests of 236 

, steam, care of 175 

, clearance of, method of measuring 186 

, commercial efficiency of 181 

, compound, tests of 189 

, constant, use of 158 

, cylinder losses of 184 

, friction test of, 1 79 

, horse-power of 157 

-testing 165 

Equalizing the work of a compound engine 191 



INDEX. 28l 

PAGE 

Equivalent elongation 90, 

evaporation, definition of 123 

Errors of the indicator. . . 146 

Exercise, calculations from an indicator-card 163 

with measuring-instruments 19 

with the planimeter, (a) 15 

. w 15 

with steam-calorimeters, 54 

Experiments with flow of steam through an orifice 30 

Extensometer, Riehle Yale, the 89 

use of the 100 

F 

Flow of gases, measurement of 29 

steam, experiments on. 30 

, formulae for 30 

water over weirs, formulae for 25 

through orifices, formulae for 21 

Flue-gas analysis 1 25 

Form for boiler tests 134 

calibration of gages .... 35 

thermometers 42 

water-meters 28 

efficiency tests of hoists 65 

screws 62 

exercise with measuring-instruments 19 

experiment on stem-immersion of thermometers 44 

flow of water 23 

friction test of the steam-engine 180 

indicated horse-power test 175 

indicator-spring testing 1 50 

locomotive link-motion experiment 173 

locomotive-testing 202 

throttling-calorimeter 51 

valve-setting 170 

of specimen for tension tests 96 

Formulae for flow of air 29 

steam 30 

water through an orifice 21 

over weirs 25 



282 INDEX. 

PAGE 

Friction test of the steam-engine 1 79 

, form for 180 

Fuel calorimeters 124 

, heating value of. ... . 124 



Gage, hook 26 

, laying-off 93 

, pressure 33 

, Bristol recording 39 

, calibration of, by comparison with standard 34 

gage- tester. ... 36 

, form for 35 

, correction of 37 

, vacuum. 34 

Gas-engines, tests of 236 

Gases, measurement of 29 

Graphical logs of boiler tests 126 

Graphic presentation of results 3 

H 

Head over weirs, measurement of 26 

Heads of water, comparison of, table 264 

Heating value of fuels 1 24 

Henning portable recorder, the 91 

Hoists, efficiency of , 63 

, form for 65 

Hook-gage, the 26 

Horse-power of boilers 124 

the steam-engine 157 

test, indicated 173 

, form for 175 

Hydraulic dynamometer, Emery 87 

machinery, testing of 224 

testing-machine, Emery. 77 

, Riehle 76 

I 

Impact tests of materials 117 

Impulse-wheels, advanced work on 235 



INDEX. 283 

PAGE 

Impulse-wheels, tests of 232 

Indicator-card, the : 150 

, calculations from 157 

, condensed directions for working up 155 

, determining per cents of stroke 152 

, locating events of stroke. . 151 

, M. E. P. of 153 

, M. E. P. by method of ordinates 153 

, M. E. P. by planimeter . 155 

diagram, (see Indicator-card), 

springs, method of testing.. 147 

, form for 150 

, steam-engine, the 139 

, choice of spring for 144 

, Crosby. -...- 139 

, errors of. 146 

, Tabor 142 

, use of , 144 

, valve-setting by 171 

Indicated horse-power test 173 

, form for 175 

Inertia, moments of, table 247 

Injectors, advanced work on 252 

, Metropolitan 246 

, Sellers 246 

, tests of 245 

Investigation of cylinder losses of the steam-engine 184 

K 
Keeping the records 2 

L 

Lap, definition of 166 

Laying-off gage 93 

Lead, definition of 166 

Le Chatelier pyrometer, the 45 

Leftel turbine-wheel, the 229 

Lineal measurement 16 

Link-motion, steam distribution of 1 72 



284 INDEX. 

PAGE 

Locomotive dynamometer. 87 

link-motion, steam distribution of 172 

-testing 192 

, A. S. M, E. standard method of 193 

-testing plants 207 

, methods of testing 210 

tests, method of conducting. . » 210 

, method of working up 212 

, tractive force of, table 2 74 

Long specimens in compression, tests of 106 

Lubricators , 176 

Lunkenheimer lubricator, the 177 

M 

Manometers 37 

Materials, strength of 70 

, weights of, table 263 

Mean effective pressure of the indicator-card 153 

by method of ordinates 153 

by planimeter 155 

Measuring-instruments, exercise with 19 

-machine, Sweet's. 17 

water, methods of , . 21 

Measurement of areas t 6 

gases 29 

head over weirs 26 

length 16 

liquids 21 

power 55 

pressure 33 

speed 5 

temperature 40 

time 4 

Melting-points of metals, table 265 

Mercurial thermometers 40 

Metals, melting-points of, table. 265 

Meters, water 27 

, calibration of 27 

, form for 28 

Method of combining indicator-cards 161 



INDEX. 285 

PAGE 

Method of instruction 1 

measuring clearance of the steam-engine 186 

gases . . 29 

liquids 21 

testing boilers 126 

in compression 104 

in tension 93 

for ultimate strength 97 

for elastic limit 100 

locomotives 210 

, A. S. M. E 193 

working up locomotive tests 212 

Metropolitan injector, the 246 

Micrometer caliper, the 16 

Miscellaneous tests 236 

Modulus of elasticity, definition of • 95 

resilience, definition of 95 

Moments of inertia, table 274 

N 
Nozzle, coefficients of discharge of 25 

O 

Olsen 100, 000- pound testing-machine 15 

Orifice, calibration of 24 

, form for. 25 

, determination of coefficient of discharge of 22 

, formulae for flow of air through an 29 

steam through an 30 

water through an 21 

P 

Paper friction-wheels, tests of , 68 

Paving-brick, rattler test for 116 

Peabody throttling calorimeter, the 47 

Pelton wheel, advanced work on 235 

, tests of 232 

Per cent of elongation, definition of ........... 96 



286 INDEX. 



PAGE 

Pipe brake. 57 

Pitot tube for measuring flow of gases 32 

Planimeter, adjustable ........ 13 

, area of the zero-circle. 13 

, directions for use of. 15 

, exercise with, (a) 15 

>(*) 15 

, polar, the 6 

, theory of 9 

Plants, locomotive-testing , 207 

Pressure-gages 33 

, calibration of 34 

, measurement of 33 

Prony brake, the . . ... 55 

, special forms of ..... . 57 

Properties of saturated steam, table 266 

Pumps, centrifugal, advanced work on 229 

, tests of. .... . 227 

, steam, advanced work on 226 

, tests of 224 

Pyrometers, copper-ball 45 

, Le Chatelier. . . 45 

R 

Rattler test for paving-brick 116 

Records, autographic 104 

, keeping the 2 

Reduction of area, definition of 96 

Reevaporation from the indicator-card 159 

Reports 2 

Resilience, modulus of, definition of 95 

Revolution-counters 6 

Riehle hydraulic testing-machine 76 

patent high-faced wedge. 71 

100,000-pound testing-machine 73 

300,000-pound testing-machine 71 

Rise and fall of mercurial thermometers, rate of 43 

Rules for care of thermometers 40 

use of the indicator 144 



INDEX. 287 

S 

PAGE 

Screws, efficiency test of , 60 

, form for 62 

Sellers injector, the 246 

Separating calorimeter 51 

, use of 52 

Short specimens in compression 104 

Slide-valve engines, valve-setting for 168 

Slippage of belts 67 

Specimens for tension tests, form of 96 

wire rope in tension 115 

Speed-counters 5 

, measurement of 5 

-recorder, the Boyer 5 

Springs, indicator, choice of 144 

, method of testing 147 

Standard method of testing boilers, A. S. M. E 126 

locomotives, A. S. M. E 193 

Steam-boiler testing. 123 

distribution of locomotive link-motion 172 

, form for 173 

-engine, care of 175 

, clearance of 186 

, commercial efficiency of 181 

, cylinder losses of 184 

, friction test of 179 

indicator, the 139 

testing 165 

, advanced work in 188 

, experiments on flow of 30 

, formulae for flow of 30 

, properties of saturated, table 266 

pumps, tests of 224 

turbines, tests of 253 

, the De Laval 253 

Stem-immersion of mercurial thermometers, experiment on 44 

Stops, method of making 4 

Strength of materials 70 

Stress-strain diagrams 102 

Sweet's measuring-machine , . . , . . , 17 



288 INDEX. 

T 

PAGE 

Table of circumferences and areas of circles 257 

coefficients of discharge of rectangular weirs 275 

decimal equivalents 262 

Fahrenheit and centigrade thermometer-scales 273 

melting-points of metals 265 

moments of inertia „ . 274 

properties of saturated steam . . 266 

tractive force of locomotives 274 

weights of various materials 263 

water. 264 

Tabor indicator, the 142 

Tachometers . 6 

Temperature, measurement of 40 

Tension tests of materials , 93 

, form of specimen for , 96 

Testing indicator-springs 147 

, form for 150 

-machines 70 

, brick 116 

, Emery hydraulic 77 

, impact 117 

, Olsen cement 88 

, Olsen 100,000-pound 75 

, Riehle hydraulic 76 

, Riehle 100,000- pound 73 

, Riehl& 300,000-pound 71 

, Riehle wire 87 

of hydraulic machinery 224 

of steam-boilers , 123 

of steam-engines 165 

-plants, locomotive 207 

Tests of air-compressors 238 

belts 65 

cement Ill 

centrifugal pumps 227 

combined engine and boiler 218 

compound engines , 189 

erficiency of hoists 63 

screws. ........... , f .... . 60 



INDEX. 289 

PAGE 

Tests of gas-engines , 236 

impulse-wheels 232 

indicated horse-power 173 

injectors 245 

locomotives 192 

materials by cold-bending. ...» . . . 121 

by drifting 122 

in compression 104 

in cross-bending 109 

in impact 117 

in tension k 93 

paving-brick 116 

steam-engines, compound 189 

, efficiency 181 

, friction 1 79 

steam-pumps 224 

steam-turbines 253 

turbine- wheels 229 

wire rope 115 

Theory of the planimeter 9 

Thermometers, calibration of, by comparison with standard. ..... 41 

steam-pressure 42 

, form for 42 

, comparison of scales, table 273 

, effect of stem-immersion 44 

, mercurial 40 

, rate of rise and fall 43 

, rules for care of 40 

Throttling calorimeter, the , 47 

, form for 51 

, limitations of 49 

, use of 50 

Time, measurement of 4 

-signals 4 

Tractive force of locomotives, table 274 

Transmission-dynamometers 58 

Transverse tests of materials 109 

Turbines, steam, tests of 253 

, the De Laval 253 

Turbine- wheels, tests of 229 

, advanced work on 231 



290 INDEX. 

U 

. PAGE 

Ultimate strength, definition of 94 

, method of testing for 97 

U-tubes, use of 37 

V 

Vacuum-gages 34 

Valve-setting 165 

by indicator. . . . 171 

, form for 170 

, general definitions 166 

, specific directions for 167 

Velocity, flow of gases by method of 32 

Vernier caliper, the 16 

W 

Water, comparison of heads of, table ,. , 264 

, formulae for flow of, over weirs 25 

, through orifices 21 

-meters, calibration of 27 

, form for 28 

, methods of measuring 21 

, weights of, table 264 

Wedge, Riehle patent high-faced 71 

Weights of materials, table 263 

steam from the indicator-diagram 158 

water, table 264 

Weirs, formulae for flow of water over 25 

, measurement of head over 26 

, coefficients of discharge of, table 275 

Wire rope, preparation of specimens 115 

, tests of, in impact 117 

-testing machine, Riehle 87 

Working up indicator-cards, directions for 157 

locomotive tests, directions for „ 212 

Y 

Yield-point, definition of 94 

Z 

Zero-circle of the planimeter 13 

Zero-reading of the hook-gage 26 



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Phelps's Practical Marine Surveying 8vo, 

Powell's Army Officer's Examiner 12mo, 

Reed's Signal Service. 

Sharpe's Subsisting Armies 18mo, morocco, 

Very's Navies of the World 8vo, half morocco, 

Wheeler's Siege Operations 8vo, 

Winthrop's Abridgment of Military Law 12ino, 

Woodhull's Notes on Military Hygiene 12mo, 

Young's Simple Elements of Navigation.. 12mo, morocco flaps, 

first edition 

ASSAYING. 

Smelting — Ore Dressing— Alloys, Etc. 

Fletcher's Quant. Assaying with the Blowpipe.. 12mo, morocco, 1 50 

Furman's Practical Assaying 8vo, 3 00 

Kunhardt's Ore Dressing 8vo, 1 50 

* Mitchell's Practical Assaying, (Crookes.) 8vo, 10 00 

O'Driscoll's Treatment of Gold Ores 8vo, 2 CO 

Ricketts and Miller's Notes on Assaying 8vo, 3 00 

Thurston's Alloys, Brasses, and Bronzes 8vo, 2 50 

Wilson's Cyanide Processes 12mo, 1 50 

The Chlorination Process 12mo, 1 50 

ASTRONOMY. 

Practical, Theoretical, and Descriptive. 

Craig's Azimuth 4to, 3 50 

Doolittle's Practical Astronomy 8vo, 4 00 

Gore's Elements of Geodesy 8vo, 2 50 



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Hay ford's Text-book of Geodetic Astronomy 8vo. 

Michie and Harlow's Practical Astronomy 8vo, $3 00 

White's Theoretical and Descriptive Astronomy 12mo, 2 00 

BOTANY. 

Gardening for Ladies, Etc. 

Baldwin's Orchids of New England 8vo, 1 50 

Loudon's Gardening for Ladies. (Downing.) 12mo, 1 50 

Thome's Structural Botany 18mo, 2 25 

We^termaier's General Botany. (Schneider.) 8vo, 2 00 

BRIDGES, ROOFS, Etc. 

Cantilever— Draw— Highway — Suspension. 
(See also Engineering, p. 6.) 

Boiler's Highway Bridges 8vo, 2 00 

* " The Thames River Bridge 4to, paper, 5 00 

Burr's Stresses in Bridges. ... 8vo, 3 50 

Crehore's Mechanics of the Girder 8vo, 5 00 

Dredge's Thames Bridges 7 parts, per part, 1 25 

Du Bois's Stresses iu Framed Structures 4to, 10 00 

Foster's Wooden Trestle Bridges 4to, 5 00 

Greene's Arches in Wood, etc 8vo, 2 50 

Bridge Trusses 8vo, 2 50 

Roof Trusses... ...8vo, 1 25 

Howe's Treatise on Arches 8vo, 4 00 

Johnson's Modern Framed Structures 4to, 10 00 

Merriman & Jacoby's Text-book of Roofs and Bridges. 

Parti., Stresses 8vo, 2 50 

Merriman & Jacoby's Text-book of Roofs and Bridges. 

Part II.. Graphic Statics ~. 8vo, 2 50 

Merriman & Jacoby's Text-book of Roofs and Bridges. 

Part III., Bridge Design Svo, 2 50 

Merriman & Jacoby's Text- book of Roofs and Bridges. 

Part IV., Continuous, Draw, Cantilever, Suspension, and 

Arched Bridges 8vo, 2 50 

* Morison's The Memphis Bridge Oblong 4to, 10 00 

4 



WaddelPs Iron Highway Bridges 8vo, $4 00 

De Pontibus (a Pocket-book for Bridge Engineers). 

Wood's Construction of Bridges and Roofs 8vo, 2 00 

Wright's Designing of Draw Spans 8vo, 2 50 

CHEMISTRY. 

Qualitative — Quantitative- Organic — Inorganic, Etc. 

Adriance's Laboratory Calculations 12mo, 1 25 

Allen's Tables for Iron Analysis 8vo, 3 00 

Austen's Notes for Chemical Students 12mo, 1 50 

Bolton's Student's Guide in Quantitative Analysis 8vo, 1 50 

Classen's Analysis by Electrolysis. (HerrickandBoltwood.).8vo, 3 00 

Crafts's Qualitative Analysis. (Schaeffer.) 12mo, 1 50 

Drechsel's Chemical Reactions. (Merrill.) 12mo, 1 25 

Fresenius's Quantitative Chemical Analysis. (Allen.) 8vo, 6 00 

Qualitative " " (Johnson.) 8vo, 3 00 

(Wells) Trans. 16th. 

German Edition 8vo, 5 00 

Fuerte's Water and Public Health 12mo, 1 50 

Gill's Gas and Fuel Analysis 12mo, 1 25 

Hammarsten's Physiological Chemistry. (Mandel.) 8vo, 4 00 

Helm's Principles of Mathematical Chemistry. (Morgan). 12mo, 1 50 

Kolbe's Inorganic Chemistry 12mo, 1 50 

Ladd's Quantitative Chemical Analysis 12mo, 1 00 

Landauer's Spectrum Analysis. (Tingle.) 8vo, 3 00 

Mandel's Bio-chemical Laboratory 12mo, 1 50 

Mason's Water-supply 8vo, 5 00 

" Analysis of Potable Water. (In the press.) 

Miller's Chemical Physics 8vo, 2 00 

Mixter's Elementary Text-book of Chemistry 12mo, 1 50 

Morgan's The Theory of Solutions and its Results 12mo, 1 00 

Nichols's Water-supply (Chemical and Sanitary) 8vo, 2 50 

O'Brine's Laboratory Guide to Chemical Analysis 8vo, 2 00 

Perkins's Qualitative Analysis 12mo, 1 00 

Pinner's Organic Chemistry. (Austen.) 12mo, 1 50 

Poole's Calorific Power of Fuels 8vo, 3 00 

Ricketts and Russell's Notes on Inorganic Chemistry (Non- 
metallic) Oblong 8vo, morocco, 75 



Uuddiiiian'a Incompatibilities in Prescriptions 8vo, 

Schimpf s Volumetric Analysis 12mo, 

Spencer's Sugar Manufacturer's Handbook . 12mo, morocco flaps, 
Handbook for Chemists of Beet Sugar House. 

12mo, morocco, 

Stockbridge's Rocks and Soils .8vo, 

Troilius's Chemistry of Iron 8vo, 

Wells's Inorganic Qualitative Analysis 12mo, 

" Laboratory Guide in Qualitative Chemical Analysis, 8vo, 

Wiechmann's Chemical Lecture Notes 12mo, 

Sugar Analysis 8vo, 

Wulling's Inorganic Phar. and Med. Chemistry 12mo, 

DRAWING. 

Elementary — Geometrical — Topographical. 

Hill's Shades and Shadows and Perspective 8vo, 

MacCord's Descriptive Geometry 8vo, 

" Kinematics 8vo, 

11 Mechanical Drawing 8vo, 

Mahan's Industrial Drawing. (Thompson.) 2 vols., 8vo, 

Reed's Topographical Drawing. (II. A.) 4to, 

Reid's A Course in Mechanical Drawing 8vo. 

" Mechanical Drawing and Elementary Machine Design. 

8vo. 

Smith's Topographical Drawing. (Macmillan.) , . .8vo, 

Warren's Descriptive Geometry 2 vols., 8vo, 

" Drafting Instruments 12mo, 

1 ' Free-hand Drawing 1 2mo, 

" Higher Linear Perspective 8vo, 

" Linear Perspective 12mo, 

" Machine Construction .2 vols., 8vo, 

" Plane Problems , 12mo, 

" Primary Geometry 12mo, 

" Problems and Theorems 8vo, 

" Projection Drawing 12mo, 

'* Shades and Shadows 8vo, 

" Stereotomy— Stone Cutting 8vo, 

Whelpley's Letter Engraving 12mo, 

6 



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ELECTRICITY AND MAGNETISM. 

Illumination— Batteries — Physics. 

Anthony and Brackett's Text- book of Physics (Magie). . . 8vo, $4 00 

Barker's Deep-sea Soundings 8vo, 2 00 

Benjamin's Voltaic Cell 8vo, 3 00 

History of Electricity 8vo 3 00 

Cosmic Law of Thermal Repulsion 18mo, 75 

Crehore aud Squier's Experiments with a New Polarizing Photo- 
Chronograph 8vo, 3 00 

* Dredge's Electric Illuminations. . . .2 vols., 4to, half morocco, 25 00 

Vol. II 4to, 7 50 

Gilbert's De magnete. (Mottelay.) 8vo, 2 50 

Holman's Precision of Measurements 8vo, 2 00 

Michie's Wave Motion Relating to Sound and Light, 8vo, 4 00 

Morgan's The Theory of Solutions and its Results 12mo, 1 00 

Niaudet's Electric Batteries. (Fishback.) 12mo, 2 50 

Reagan's Steam and Electrical Locomotives 12mo, 2 00 

Thurston's Stationary Steam Engines for Electric Lighting Pur- 
poses 12mo, 1 50 

Tillman's Heat 8vo, 1 50 

ENGINEERING. 

Civil — Mechanical— Sanitary, Etc. 

(See also Bridges, p. 4 ; Hydraulics, p. 8 ; Materials of En- 
gineering, p. 9 ; Mechanics akd Machinery, p. 11 ; Steam Engines 
and Boilers, p. 14.) 

Baker's Masonry Construction 8vo, 5 00 

Surveying Instruments 12mo, 3 00 

Black's U. S. Public Works 4to, 5 00 

Brook's Street Railway Location 12mo, morocco, 1 50 

Butts's Engineer's Field-book 12mo, morocco, 2 50 

Byrne's Highway Construction 8vo, 7 50 

Inspection of Materials and Workmanship. 12mo, mor. 

Carpenter's Experimental Engineering 8vo, 6 00 

Church's Mechanics of Engineering — Solids and Fluids 8vo, 6 00 

Notes and Examples in Mechanics 8vo, 2 00 

Crandall's Earthwork Tables 8vo, 1 50 

1 * The Transition Curve 12mo, morocco, 1 50 

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* Dredge's Perm. Railroad Construction, etc. . . Folio, half mor., $20 00 

* Drinker's Tunnelling 4to, half morocco, 

Eissler's Explosives — Nitroglycerine and Dynamite 8vo, 

Fowler's Coffer-dam Process for Piers 8vo. 

Gerhard's Sanitary House Inspection 16mo, 

Godwin's Railroad Engineer's Field-book. 12mo, pocket-bk. form, 

Gore's Elements of Geodesy 8vo, 

Howard's Transition Curve Field-book . . .12mo, morocco flap, 

Howe's Retaining Walls (New Edition.) 12ino, 

Hudson's Excavation Tables. Vol. II , 8vo, 

Hutton's Mechanical Engineering of Power Plants 8vo, 

Johnson's Materials of Construction 8vo, 

" Stadia Reduction Diagram. .Sheet, 22£ X 28£ inches, 

" Theory and Practice of Surveying 8vo, 

Kent's Mechanical Engineer's Pocket-book 12mo, morocco, 

Kiersted's Sewage Disposal 12mo, 

Kirkwood's Lead Pipe for Service Pipe 8vo, 

Mahan's Civil Engineering. (Wood.) 8vo, 

Merriman and Brook's Handbook for Surveyors. . . .12mo, mor., 

Merriman's Geodetic Surveying 8vo, 

" Retaining Walls and Masonry Dams 8vo, 

Mosely's Mechanical Engineering. (Mahan.) 8vo, 

Nagle's Manual for Railroad Engineers 12mo, morocco, 

Patton's Civil Engineering ,8vo, 

" Foundations 8vo, 

Rockwell's Roads and Pavements in France 12mo, 

Ruffner's Non-tidal Rivers= 8vo, 

Searles's Field Engineering 12mo, morocco flaps, 

" Railroad Spiral 12mo, morocco flaps, 

Siebert and Biggin's Modern Stone Cutting and Masonry. . .8vo, 
Smith's Cable Tramways 4to, 

" Wire Manufacture and Uses 4to, 

Spalding's Roads and Pavements 12mo, 

Hydraulic Cement 12mo, 

Thurston's Materials of Construction 8vo, 

* Trautwine's Civil Engineer's Pocket-book. ..12mo, mor. flaps, 

* * 4 Cross-section Sheet, 

* •' Excavations and Embankments 8vo, 

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* Trautwine's Laying Out Curves ' 12mo, morocco, $2 50 

Waddell's De Pontibus (A Pocket-book for Bridge Engineers). 

12mo, morocco, 

Wait's Engineering and Architectural Jurisprudence 8vo, 

Sbeep, 

" Law of Field Operation in Engineering, etc 8vo. 

Warren's Stereotomy — Stone Cutting 8vo, 

Webb s Engineering Instruments 12mo, morocco, 

Wegmann's Construction of Masonry Dams 4to, 

Wellington's Location of Railways 8vo, 

Wheeler's Civil Engineering 8vo, 

WolfTs Windmill as a Prime Mover 8vo, 

HYDRAULICS. 

Water-wheels— Windmills— Service Pipe— Drainage, Etc. 
(See also Engineering, p. 6. ) 

Bazin's Experiments upon the Contraction of the Liquid Vein 

(Trautwine) 8vo, 2 00 

Bovey's Treatise on Hydraulics 8vo, 4 00 

Coffin's Graphical Solution of Hydraulic Problems 12mo, 2 50 

Ferrel's Treatise on the Winds, Cyclones, and Tornadoes. . .8vo, 4 00 

Fuerte's Water and Public Health 12mo, 1 50 

Ganguillet&Kutter'sFlow of Water. (Hering& Trautwine. ).8vo, 4 00 

Hazen's Filtration of Public Water Supply 8vo, 2 00 

Herschel's 115 Experiments 8vo, 2 00 

Kiersted's Sewage Disposal 12mo, 1 25 

Kirkwood's Lead Pipe for Service Pipe 8vo, 1 50 

Mason's Water Supply 8vo, 5 00 

Merriman's Treatise on Hydraulics. . , 8vo, 4 00 

Nichols's Water Supply (Chemical and Sanitary) 8vo, 2 50 

Ruffner's Improvement for Non-tidal Rivers 8vo, 1 25 

Wegmann's Water Supply of the City of New York 4to, 10 00 

Weisbach's Hydraulics. (Du Bois.) 8vo, 5 00 

Wilson's Irrigation Engineering 8vo, 4 00 

Hydraulic and Placer Mining 12mo, 2 00 

Wolff's Windmill as a Prime Mover 8vo, 3 00 

Wood's Theory of Turbines 8vo, 2 50 

MANUFACTURES. 

Aniline — Boilers— Explosives— Iron— Sugar — Watches- 
Woollens, Etc. 

Allen's Tables for Iron Analysis 8vo, 3 00 

Beaumont's Woollen and Worsted Manufacture 12mo, 1 50 

Bolland's Encyclopaedia of Founding Terms 12mo, 3 00 

9 



Bolland's The Iron Founder 12mo, 

Supplement 12mo, 

Booth's Clock and Watch Maker's Manual 12mo, 

Bouvier's Handbook on Oil Painting 12mo, 

Eissler's Explosives, Nitroglycerine and Dynamite 8vo, 

Ford's Boiler Making for Boiler Makers 18mo, 

Metcalfe's Cost of Manufactures 8vo, 

Metcalf 's Steel— A Manual for Steel Users 12mo, 

Reimann's Aniline Colors. (Crookes.) 8vo, 

* Reisig's Guide to Piece Dyeing 8vo, 

Spencer's Sugar Manufacturer's Handbook 12mo, inor. flap, 

" Handbook for Chemists of Beet Houses. 

12mo, mor. flap, 

Svedelius's Handbook for Charcoal Burners 12mo, 

The Lathe and Its Uses 8vo, 

Thurston's Manual of Steam Boilers 8vo, 

Walke's Lectures on Explosives 8vo, 

West's American Foundry Practice , 12mo, 

Moulder's Text-book 12mo, 

Wiechmann's Sugar Analysis 8vo, 

Woodbury's Fire Protection of Mills 8vo, 



MATERIALS OF ENGINEERING. 

Strength — Elasticity — Resistance, Etc. 
{See also Engineering, p. 6.) 

Baker's Masonry Construction 8vo, 

Beardslee and Kent's Strength of Wrought Iron 8vo, 

Bovey's Strength of Materials 8vo, 

Burr's Elasticity and Resistance of Materials . . .8vo, 

Byrne's Highway Construction 8vo, 

Carpenter's Testing Machines and Methods of Testing Materials. 

Church's Mechanics of Engineering — Solids and Fluids 8vo, 

Du Bois's Stresses in Framed Structures 4to, 

Hatfield's Transverse Strains 8vo, 

Johnson's Materials of Construction 8vo, 

Lanza's Applied Mechanics 8vo, 

Merrill's Stones for Building and Decoration 8vo, 

Merriman's Mechanics of Materials . . . .8vo, 

Stnngth of Materials 12mo, 

Pattou's Treatise on Foundations 8vo, 

Rockwell's Roads and Pavements in France 12mo, 

Spalding's Roads and Pavements 12mo, 

Thurston's Materials of Construction , 8vo, 

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Thurston's Materials of Engineering B vols., 8vo, $8 00 

Vol. L, Non-metallic 8vo, 2 00 

Vol. IL, Iron and Steel 8vo, 3 50 

Vol. III., Alloys, Brasses, and Bronzes 8vo, 2 50 

Weyrauch's Strength of Iron and Steel. (Du Bois.) 8vo, 1 50 

Wood's Resistance of Materials 8vo, 2 00 

MATHEMATICS. 

Calculus— Geometry — Trigonometry, Etc. 

Baker's Elliptic Functions 8vo, 1 50 

Ballard's Pyramid Problem 8vo, 1 50 

Barnard's Pyramid Problem 8vo, 1 50 

Bass's Differential Calculus 12mo, 4 00 

Brigg's Plane Analytical Geometiy 12mo, 1 00 

Chapman's Theory of Equations 12mo, 1 50 

Chessin's Elements of the Theory of Functions. 

Compton's Logarithmic Computations 12mo, 1 50 

Craig's Linear Differential Equations 8vo, 5 00 

Davis's Introduction to the Logic of Algebra 8vo, 1 50 

Halsted's Elements of Geometry t ..8vo, 175 

" Synthetic Geometry 8vo, 150 

Johnson's Curve Tracing 12mo, 1 00 

11 Differential Equations— Ordinary and Partial 8vo, 3 50 

" Integral Calculus 12mo, 1 50 

Unabridged. 

" Least Squares , 12mo, 1 50 

Ludlow's Logarithmic and Other Tables. (Bass.) 8vo, 2 00 

Trigonometry with Tables. (Bass.) 8vo, 3 00 

Mahan's Descriptive Geometry (Stone Cutting) 8vo, 1 50 

Merriman and Woodward's Higher Mathematics. 8vo, 5 00 

Merriman's Method of Least Squares 8vo, 2 00 

Parker's Quadrature of the Circle 8vo, 2 50 

Rice and Johnson's Differential and Integral Calculus, 

2 vols, inl, 12mo, 2 50 

" Differential Calculus 8vo, 3 00 

" Abridgment of Differential Calculus 8vo, 150 

Searles's Elements of Geometry 8vo, 1 50 

Totten's Metrology 8vo, 2 50 

Warren's Descriptive Geometry 2 vols., 8vo, 3 50 

" Drafting Instruments 12mo, 125 

" Free-hand Drawing 12mo, 1 00 

11 Higher Linear Perspective 8vo, 3 50 

" Linear Perspective. 12mo, 100 

n Primary Geometry 12mo, 75 

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Warren's Plane Problems. 12mo, $1 25 

Problems and Theorems 8vo, 2 50 

11 Projection Drawing 12mo, 150 

Wood's Co-ordinate Geometry 8vo, 2 00 

■' Trigonometry 12mo, 1 00 

Woolf s Descriptive Geometry Royal 8vo, 3 00 

MECHANICS- MACHINERY. 

Text-books and Practical Works. 
{See also Engineering, p. 6.) 

Baldwin's Steam Heating for Buildings 12mo, 

Benjamin's Wrinkles and Recipes 12mo, 

Carpenter's Testing Machines and Methods of Testing 

Materials 8vo. 

Chordal's Letters to Mechanics 12mo, 

Church's Mechanics of Engineering 8vo, 

Notes and Examples in Mechanics 8vo, 

Crehore's Mechanics of the Girder 8vo, 

Cromwell's Belts and Pulleys 12mo, 

Toothed Gearing 12mo, 

Compton's First Lessons in Metal Working 12mo, 

Dana's Elementary Mechanics 12mo, 

Dingey's Machinery Pattern Making 12mo, 

Dredge's Trans. Exhibits Building, World Exposition, 

4to, half morocco, 

Du Bois's Mechanics. Vol. I., Kinematics 8vo, 

Vol. II.. Statics 8vo, 

Vol, III., Kinetics 8vo, 

Fitzgerald's Boston Machinist 18mo, 

Flather's Dynamometers .12mo, 

" Rope Driving 12mo, 

Hall's Car Lubrication 12mo, 

Holly's Saw Filing 18mo, 

Johnson's Theoretical Mechanics. An Elementary Treatise. 
{In the press.) 

Jones Machine Design. Part L, Kinematics 8vo, 1 50 

" " " Part II., Strength and Proportion of 

Machine Parts. 

Lanza's Applied Mechanics 8vo, 7 50 

MacCord's Kinematics 8vo, 5 00 

Merriman's Mechanics of Materials 8vo, 4 00 

Metcalfe's Cost of Manufactures 8vo, 5 00 

Michie's Analytical Mechanics 8vo, 4 00 

Mosely's Mechanical Engineering. (Mahan.) 8vo, 5 00 

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Richards's Compressed Air 12mo, $1 50 

Robinson's Principles of Mechanism 8vo, 3 00 

Smith's Press-working of Metals 8vo, 3 00 

The Lathe and Its Uses 8vo, 6 00 

Thurston's Friction and Lost Work 8vo, 3 00 

The Animal as a Machine , 12mo, 1 00 

Warren's Machine Construction 2 vols., 8vo, 7 50 

Weisbach's Hydraulics and Hydraulic Motors. (Du Bois.)..8vo, 5 00 
" Mechanics of Engineering. Vol. III., Part I., 

Sec. I. (Klein.) 8vo, 5 00 

Weisbach's Mechanics of Engineering Vol. III., Part I., 

Sec. II (Klein.) 8vo, 5 00 

Weisbach's Steam Engines. (Du Bois.) 8vo, 5 00 

Wood's Analytical Mechanics 8vo, 3 00 

11 Elementary Mechanics 12mo, 125 

" " " Supplement and Key 125 



METALLURGY. 

Iron— Gold— Silver — Alloys, Etc. 

Allen's Tables for Iron Analysis 8vo, 

Egleston's Gold and Mercury 8vo, 

" Metallurgy of Silver 8vo, 

* Kerl's Metallurgy — Copper and Iron 8vo, 

* < 4 Steel, Fuel, etc 8vo, 

Kunhardt's Ore Dressing in Europe 8vo, 

Metcalf's Steel — A Manual for Steel Users 12m o, 

O'Driscoll's Treatment of Gold Ores 8vo, 

Thurston's Iron and Steel 8vo, 

Alloys 8vo, 

Wilson's Cyanide Processes 12mo, 

MINERALOGY AND MINING. 

Mine Accidents — Ventilation — Ore Dressing, Etc. 

Barringer's Minerals of Commercial Value oblong morocco, 2 50 

Beard's Ventilation of Mines .. 12mo, 2 50 

Boyd's Resources of South Western Virginia 8vo, 3 00 

" Map of South Western Virginia Pocket-book form, 2 00 

Brush and Penfield's Determinative Mineralogy 8vo, 3 50 

Chester's Catalogue of Minerals 8vo, 1 25 

paper, 50 

" Dictionary of the Names of Minerals 8vo, 3 00 

Dana's American Localities of Minerals 8vo, 1 00 

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Dana's Descriptive Mineralogy. (E. S.) . . . -8vo, half morocco, $12 50 

11 Mineralogy and Petrography (J.D.) 12rno, 2 00 

11 Minerals and How to Study Them. (E. S.) 12mo, 1 50 

" Text-book of Mineralogy. (E. S.) 8vo, 3 50 

*Drinker's Tunuelliug, Explosives, Compounds, and Rock Drills. 

4to, half morocco, 25 00 

Eglestou's Catalogue of Minerals and Synonyms 8vo, 2 50 

Eissler's Explosives — Nitroglycerine and Dynamite 8vo, 4 00 

Goody car's Coal Mines of the Western Coast 12mo, 2 50 

Hussak's Rock forming Minerals. (Smith.) 8vo, 2 00 

Ihlseng's Manual of Mining 8vo, 4 00 

Kunhardt's Ore Dressing in Europe 8vo, 1 50 

O'Driscoll's Treatment of Gold Ores . . 8vo, 2 00 

Roseubusch's Microscopical Physiography of Minerals and 

Rocks (Iddings ) 8vo, 5 00 

Sawyer's Accidents in Mines 8vo, 7 00 

Stockbridge's Rocks and Soils , . . . .8vo, 2 50 

Walke's Lectures on Explosives 8vo, 4 00 

Williams's Lithology . 8vo, 3 00 

Wilson's Mine Ventilation 161110, 1 25 

" Hydraulic and Placer Mining 12mo. 

STEAM AND ELECTRICAL ENGINES, BOILERS, Etc. 

Stationary— Marine— Locomotive— Gas Engines, Etc. 

(See also Engineering, p. 6.) 

Baldwin's Steam Heating for Buildings 12mo, 

Clerk's Gas Engine t 12mo ; 

Ford's Boiler Making for Boiler Makers 18mo, 

Hemen way's Indicator Practice 12mo. 

Hoadley's Warm-blast Furuace 8vo, 

Kneass's Practice and Theory of the Injector 8vo, 

MacCord's Slide Valve 8vo, 

* Maw's Marine Engines Folio, half morocco, 

Meyer's Modern Locomotive Construction 4to, 

Peabody and Miller's Steam Boilers 8vo, 

Peabody's Tables of Saturated Steam , 8vo, 

" Thermodynamics of the Steam Engine 8vo, 

" Valve Gears for the Steam Engine 8vo, 

Pray's Twenty Years with the Indicator Royal 8vo, 

Pupiii and Osterberg's Thermodynamics 12mo, 

Reagan's Steam and Electrical Locomotives 12mo, 

Rontgeu's Thermodynamics. (Du Bois.) 8vo, 

Sinclair's Locomotive Running 12mo, 

Thurston's Boiler Explosion 12mo, 

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Thurston's Engine and Boiler Trials 8vo, $5 00 

Manual of the Steam Engine. Part L, Structure 

and Theory 8vo, 7 50 

Manual of the Steam Engine. Part II., Design, 

Construction, and Operation 8vo, 7 50 

2 parts, 12 00 

Philosophy of the Steam Engine 12mo, 75 

Reflection on the Motive Power of Heat. (Carnot.) 

12mo, 1 50 

Stationary Steam Engines 12mo, 1 50 

" Steam-boiler Construction and Operation 8vo, 5 00 

Spangler's Valve Gears 8vo, 2 50 

Trowbridge's Stationary Steam Engines 4to, boards, 2 50 

Weisbach's Steam Engine. (Du Bois.) 8vo, 5 00 

Whitham's Constructive Steam Engineering 8vo, 10 00 

Steam-engine Design 8vo, 5 00 

Wilson's Steam Boilers. (Flather.) 12mo, 2 50 

Wood's Thermodynamics, Heat Motors, etc 8vo, 4 00 

TABLES, WEIGHTS, AND MEASURES. 

For Actuaries, Chemists, Engineers, Mechanics— Metric 

Tables, Etc. 

Adriance's Laboratory Calculations 12mo, 1 25 

Allen's Tables for Iron Analysis 8vo, 3 00 

Bixby's Graphical Computing Tables Sheet, 25 

Compton's Logarithms 12mo, 1 50 

Crandall's Railway and Earthwork Tables 8vo, 1 50 

Egleston's Weights and Measures 18mo, 75 

Fisher's Table of Cubic Yards Cardboard, 25 

Hudson's Excavation Tables. Vol. II 8vo, 1 00 

Johnson's Stadia and Earthwork Tables 8vo, 1 25 

Ludlow's Logarithmic and Other Tables. (Bass.) 12mo, 2 00 

Thurston's Conversion Tables 8vo, 1 00 

Totteu's Metrology 8vo, 2 50 

VENTILATION. 

Steam Heating— House Inspection— Mine Ventilation. 

Baldwin's Steam Heating 12ino, 2 50 

Beard's Ventilation of Mines 12mo, 2 50 

Carpenter's Heating and Ventilating of Buildings 8vo, 3 00 

Gerhard's Sanitary House Inspection Square 16mo, 1 00 

Mott's The Air We Breathe, and Ventilation 16mo, 1 00 

Reid's Ventilation of American Dwellings 12mo, 1 50 

Wilson's Mine Ventilation . . . 16mo, 1 25 

15 



MISCELLANEOUS PUBLICATIONS. 

Alcott's Gems, Sentiment, Language Gilt edges, $5 00 

Bailey's The New Tale of a Tub 8vo, 75 

Ballard's Solution of the Pyramid Problem 8vo, 1 50 

Barnard's The Metrological System of the Great Pyramid. ,8vo, 1 50 

Davis's Elements of Law 8vo, 2 00 

Emmou's Geological Guide-book of the Rocky Mountains. .8vo, 1 50 

Fen-el's Treatise on the Winds 8vo, 4 00 

Haines's Addresses Delivered before^the Am. Ry. Assn. ..12mo. 2 50 

Mott's The Fallacy of the Present Theory of Sound. .Sq. 16mo, 1 00 

Perkins's Cornell University Oblong 4to, 1 50 

Ricketts's History of Rensselaer Polytechnic Institute 8vo, 3 00 

Rotherham's The New Testament Critically Emphasized. 

12mo, 1 50 
" The Emphasized New Test. A new translation. 

Large 8vo, 2 00 

Totten's An Important Question in Metrology 8vo, 2 50 

Whitehouse's Lake Mceris Paper, 25 

* Wiley's Yosemite, Alaska, and Yellowstone 4to, 3 00 

HEBREW AND CHALDEE TEXT=BOOKS. 

For Schools and Theological Seminaries. 

Gesenius's Hebrew and Chaldee Lexicon to Old Testament. 

(Tregelles.) Small 4to, half morocco, 5 00 

Green's Elementary Hebrew Grammar 12mo, 1 25 

Grammar of the Hebrew Language (New Edition). 8 vo, 3 00 

Hebrew Chrestomathy 8vo, 2 00 

Letteris's Hebrew Bible (Massoretic Notes in English). 

8vo ; arabesque, 2 25 
Luzzato's Grammar of the Biblical Chaldaic Language and the 

Talmud Babli Idioms 12mo, 1 50 

MEDICAL. 

Bull's Maternal Management in Health and Disease 12mo, 1 00 

Hammarsten's Physiological Chemistry. (Mandel.) 8vo, 4 00 

Mott's Composition, Digestibility, and Nutritive Value of Food. 

Large mounted chart, 1 25 

Ruddiman's Incompatibilities in Prescriptions 8vo, 2 00 

Steel's Treatise on the Diseases of the Ox 8vo, 6 00 

Treatise on the Diseases of the Dog 8vo, 3 50 

Woodhull's Military Hygiene 12mo, 1 50 

Worcester's Small Hospitals — Establishment and Maintenance, 
including Atkinson's Suggestions for Hospital Archi- 
tecture 12mo, 1 25 

16 



OCT 3 IBS* 



